Hi, this is Ray.

Quick story about how spectacularly bad I used to be at connecting my body to my brain. In my late twenties I hit a stretch where I decided to prioritize learning above literally everything else. I was in the middle of a serious project (reading, studying, building skills for something I genuinely cared about) and I convinced myself that exercise was a luxury I couldn't afford. Every hour at the gym was an hour not studying. Every workout was time I could have spent on the actual work. So I stopped exercising. Not gradually. Just stopped. For about eight months.

The result was almost comically predictable in retrospect. My cognitive performance during that period declined steadily. Not dramatically at first. Just a slow drift where focus felt harder, retention felt weaker, and afternoon fatigue arrived earlier. I attributed all of this to the stress of the project itself… I was working hard, so of course I was tired. When the project ended and I finally went back to the gym, my brain came back within three weeks. Focus returned. Memory sharpened. The afternoon fatigue lifted. I hadn't been depleted by the project. I'd been depleted by the eight months of not moving my body.

This experience taught me something that took me longer than it should have to internalize. Your brain isn't a separate system that operates independently of the body it's housed in. It's part of your body. The condition of your body affects what your brain can do. When I sacrificed exercise to have more time for learning, I was sacrificing the condition that made the learning possible. It was like trying to speedrun a game by never healing between fights, thinking I'd save time by skipping the recovery. Except the recovery is what lets you fight the next boss. Skipping it doesn't save time. It just means the next boss kills you.

Today's newsletter is about that. What the research actually shows about physical fitness and cognitive performance, why regular exercise is one of the most reliable interventions for supporting learning, and how to actually build a practice that fits your life without treating fitness and learning as competitors for the same hours. Let's get into it.

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Let me start with what the science actually shows, because this is one of those areas where the research is much clearer than the popular conversation acknowledges.

According to a comprehensive review of exercise and cognition, physical activity participation was related to cognitive performance along eight measurement categories including perceptual skills, intelligent quotient, achievement, verbal tests, mathematics tests, memory, developmental level, and academic readiness, with results indicating a beneficial relationship of physical activity on all cognitive categories. The benefits aren't narrow. Physical activity supports basically every cognitive category researchers have measured. Same brain, same tasks, better outcomes with regular exercise than without.

The mechanism most researchers focus on involves a molecule called BDNF… brain-derived neurotrophic factor. According to the research, BDNF has been related to hippocampal volume, which has implications for learning and memory. Circulating BDNF has been related to hippocampal volume, with aerobic fitness related to the upregulation of BDNF serum levels and greater hippocampal volume among older adults. Exercise triggers BDNF release. BDNF supports hippocampal function. The hippocampus is your brain's memory center. This chain is the biology behind why fit people have measurably better memory than sedentary people of the same age.

The most striking findings involve the specific measurable effect on brain structure. According to the research on aerobic fitness and hippocampal volume, higher aerobic fitness levels were associated with the preservation of left and right hippocampal volume and better performance on their spatial memory task. This isn't subtle. Fitter people have physically bigger hippocampi than less fit people of the same age. The brain region most important for learning and memory is measurably preserved by regular exercise.

The effects extend beyond the hippocampus. According to a study on physical performance and working memory, strength, aerobic fitness, and balance are significantly associated with working memory, explaining 3–7% of its variance, irrespective of the severity of the cognitive impairment. Physical measures directly predict working memory performance. And this held even in populations with cognitive decline… meaning exercise appears to matter for cognitive function across the range from healthy to impaired.

Long-term studies show the effects persist. According to a one-year follow-up study on exercise and memory, participants of the cycling group improved more in a delayed recognition test compared to both the stretching group and the sedentary group. Recognition scores of participants with higher cardiovascular fitness at follow-up did not change significantly during the follow-up period; however, the scores of participants with lower cardiovascular fitness decreased. This is the finding I want you to sit with. The people who maintained fitness maintained their cognitive gains. The people who let fitness decline lost the cognitive benefits. The exercise isn't a one-time cognitive boost. It's an ongoing investment that pays returns for as long as you keep making it.

Here's the part that surprised me most. Different types of physical activity appear to produce somewhat different cognitive benefits. Understanding this helps you build a practice that supports your specific learning goals.

Aerobic exercise (running, cycling, swimming, brisk walking). This is the most-researched category, and the effects on memory are particularly strong. The BDNF pathway I described above responds especially well to sustained aerobic activity. If you want to preserve hippocampal function and support memory, aerobic exercise is the well-established route. Even modest amounts help… 30 minutes several times a week produces measurable benefits.

Strength training. The research here is less voluminous but consistent. Strength predicts working memory in the studies I cited above. Building muscle appears to support cognitive function through multiple pathways including improved metabolic health and hormonal effects. Strength training also improves your capacity to sustain other physical activity, which matters for long-term consistency.

Balance training. Here's the surprising one. According to a controlled study, only the balance group significantly increased in balance performance from pre- to posttest, while cardiorespiratory fitness remained unchanged in both groups. Moreover, the balance group significantly improved in memory and spatial cognition. Balance training, without any change in cardiovascular fitness, produced measurable improvements in memory and spatial cognition. The mechanism appears to involve vestibular system stimulation affecting the hippocampus and parietal cortex directly. Yoga, tai chi, and specific balance exercises count. This isn't just a cardio story.

Skill-based movement (dance, martial arts, sports). Activities that combine physical fitness with motor learning appear to produce broader cognitive benefits than either alone. The learning component of the movement engages neural systems that pure exercise doesn't. This makes activities like dance, tennis, martial arts, or team sports particularly interesting for cognitive support.

The practical implication: a mix is better than any single form. A weekly practice that includes some cardio, some strength work, some balance-oriented movement, and ideally some skill-based activity covers more of the pathways through which exercise supports cognition than a single-mode practice does.

The general benefits are one thing. Let me be specific about what this means for someone actively trying to learn something.

Acute effects support study sessions. A moderate exercise session before or between study sessions produces measurable improvements in the study that follows. According to a systematic review of acute exercise effects, physical exercise improves mental health and cognitive function. This isn't the same as long-term brain change from sustained practice. It's a same-day cognitive boost. A 20-30 minute workout before a challenging study session helps that session, above and beyond the long-term benefits of being generally fit.

Chronic effects protect your learning capacity across years. The long-term studies show that maintained fitness preserves the cognitive infrastructure you use for learning. The learner who maintains fitness across decades enters middle and old age with a brain that can still learn effectively. The sedentary learner enters those years with a brain that has been quietly declining. Same intelligence at 25. Different capacity at 55.

Sleep quality improves. As I've covered in previous newsletters, sleep is when memory consolidation happens. Regular exercise measurably improves sleep quality. This means the memory work your brain does at night is more effective. You're not just learning better during the day… you're consolidating better at night.

Stress management improves. As I've covered in the stress newsletter, chronic stress degrades learning. Regular exercise is one of the most reliable stress-management tools available. The stress reduction from exercise makes all your other learning more effective by keeping you in a better cognitive state for the actual work.

Energy for the work increases. This one is counterintuitive but real. Regular exercise doesn't drain the energy available for learning… it increases it. The fit learner has more sustained energy for study than the sedentary learner. The exercise isn't taking time from learning. It's producing more usable time overall.

Okay, the practical part. If you're convinced that fitness supports learning and want to actually build a sustainable practice, here's what works.

Start smaller than seems worth doing. The classic mistake is committing to elaborate workout routines you'll abandon within two weeks. Twenty minutes of walking most days is dramatically better than a two-hour gym routine you'll quit. Start with something you can actually sustain. Increase gradually.

Prioritize consistency over intensity. Four moderate workouts per week produces more cognitive benefit than one crushing workout followed by six days of nothing. The regularity of the stimulus matters more than the intensity of any single session. This is like leveling up in Dark Souls… consistent small experience gains beat one huge boss fight followed by nothing.

Schedule it like a meeting. Exercise that happens "when you have time" doesn't happen. Exercise scheduled at specific times, defended like other important commitments, happens. The scheduling isn't rigidity… it's the mechanism by which the habit sustains.

Mix your modes across the week. Not the same workout every day. Some cardio. Some strength. Some balance work. Some skill-based movement if possible. The variety supports different cognitive pathways and prevents the boredom that kills single-mode routines.

Do at least some of it outdoors when possible. The cognitive benefits of exercise are amplified when it happens in nature. The combination of physical activity and natural environment produces stronger stress reduction and cognitive restoration than gym-only workouts.

Pair movement with learning when it makes sense. Walks while listening to audiobooks. Podcasts during moderate cardio. Language learning apps during light stationary bike sessions. Not all exercise should be paired with learning… hard workouts benefit from full attention. But moderate movement paired with light learning content lets both activities support each other.

Match intensity to your current life demands. During heavy learning periods (finals, deadlines, intense projects), you don't have to maintain peak fitness intensity. But maintain something. Even light daily movement preserves the neural pathways that heavier training would maintain further. Don't drop exercise entirely during busy periods… reduce it if needed, but keep it.

Treat it as infrastructure, not achievement. The goal isn't to hit specific fitness milestones. The goal is to maintain the body that supports your brain. This framing produces sustainable practice better than achievement-oriented frameworks that produce burnout when goals aren't met.

Some honest caveats.

Occasional intense workouts don't compensate for sedentary weeks. The research consistently supports sustained regular activity over sporadic intense sessions. The person who works out three times a week for 30 minutes gets more cognitive benefit than the person who does one 90-minute session followed by six days of nothing.

Extreme training can be counterproductive. Very high-volume, very high-intensity training that produces chronic fatigue actually degrades cognitive performance. This is the ironic risk of over-optimizing. Moderate consistent practice beats extreme practice for cognitive support.

Exercise doesn't compensate for other missing foundations. As I've covered in the wellbeing newsletter, exercise sits alongside sleep, nutrition, social connection, and other foundational supports. It doesn't replace them. The person who exercises but doesn't sleep isn't getting the cognitive benefits their exercise would otherwise produce.

Passive activity doesn't count. Standing at a desk isn't exercise. Fidgeting isn't exercise. Walking to your car isn't exercise. The cognitive benefits documented in the research come from activity that raises your heart rate and challenges your muscles. Don't confuse general movement with the specific stimulus that produces the cognitive effects.

Here's what I want you to take from all this. The framing of exercise as competition with learning is exactly backwards. Exercise doesn't take from your learning… it supports it. The learner who exercises regularly is learning more effectively per hour than the learner who doesn't. This isn't a claim about moral virtue or lifestyle preferences. It's a claim about biology. The brain that exercise supports is a brain that learns better than the brain that exercise doesn't support.

If you've been sacrificing exercise in the name of having more time for learning, please consider that the sacrifice isn't paying what you think it is. The hours you save on the workout are producing worse hours of study. The math is against you. Adding exercise back into your life would probably produce more total learning across your available time, not less.

You don't have to become an athlete. You don't have to train intensely. You just have to move your body regularly… some cardio, some strength, some balance work, ideally with some variety across the week. This modest investment pays back across every cognitive system you use for learning, and the returns compound across decades.

Nobody builds a serious learning practice while sitting still. The body you study in is doing part of the work. Take care of it. In Naruto, even the smartest characters had to train physically… chakra isn't just mental. Your brain isn't just mental either. It's part of a body that needs maintenance to keep serving you well. Give it what it needs. The learning will follow.

Keep learning (and keep moving),

Ray