Exercise is so much more than just burning calories. The calories burned during exercise, unless you’re a professional athlete, make up quite a small portion of our total calories burned for the day; what we eat has a much greater influence on our body weight. So why should we bother to exercise? Because burning a few calories is just the tip of the iceberg – exercise is an indispensible component of a healthy lifestyle, and has profound beneficial effects, especially on the heart and brain. So if you’ve committed to a Nutritarian diet, why not add some exercise?
Here are just a few of the many benefits of daily exercise:
Protects against chronic diseases.
Regular physical activity reduces the risk of coronary heart disease and diabetes by 30-50%.  There are clear associations between physical activity and decreased risk of colon, breast, and prostate cancers, and this is thought to be in part due to effects on the insulin-like growth factor 1 (IGF-1) system.  Exercise also protects against osteoporosis, as muscle strength is the best predictor of bone strength.
Less time spent sitting.
There has been an 83% increase in sedentary jobs since 1950 – most of us are inactive for most of the day. But the human body was meant to move – our ancestors probably walked up to 12 miles each day, every day. Getting out to the gym for one hour is one hour you don’t spend sitting in a chair or on your couch – significant because prolonged sitting is associated with increased risk of diabetes and overall mortality.
Makes the brain happy.
Exercise truly is nature’s mood elevator. [4, 6] In fact, exercise has such a powerful positive effect on our mental state that it is prescribed as a treatment for major depression. Meta-analyses of clinical studies have shown that exercise alone works just as well as anti-depressant drugs or cognitive behavioral therapy for depression. Aerobic exercise plus strength training works better than aerobic exercise alone, and hatha yoga (physical yoga) is also effective at reducing depression symptoms. [7-9] Exercise affects the levels of several neurotransmitters in the brain, including increasing the production of serotonin, which is associated with feelings of well-being.  Anti-depressant drugs are often in the class of selective serotonin reuptake inhibitors (SSRIs), drugs that increase the amount of serotonin in the brain – but it turns out we can elevate serotonin naturally with exercise.
Keeps the brain thinking.
Physical activity has been consistently linked to cognitive abilities and mental alertness. In older adults, regular walking was shown to decrease the risk of cognitive impairment and contribute to maintenance of brain volume , and strength training also produces cognitive benefits. Physical activity may exert these effects in part by enhancing blood flow to the brain, which accelerates detoxification of free radicals – important since the brain is especially susceptible to oxidative damage.
Keeps the mind focused and present.
Exercise helps to bring the human mind into the present moment, becoming intensely aware of sensations in the body, rather than daydreaming. A study published last month in Science found that the human mind is daydreaming (not thinking about its current task) about 47% of the time, and also that people rated their mood as happier when they were focused on their present activity rather than engaging in other thoughts. Certain activities were better correlated to focus on the present than others - the top two were sex and exercise. [13, 14] Certain types of exercise generate more presence than others – for example, it’s more likely that you’d daydream while running on a treadmill than in a yoga class. Mindfulness practices are known to be effective for reducing depression symptoms, and breathing exercises can reduce blood pressure, stress, and anxiety. [7, 15, 16] The incorporation of these two factors into physical activity results in a greater improvement in health outcomes than physical activity alone, according to a recent meta-analysis of comparisons between hatha yoga and other forms of exercise. 
Makes the heart work smarter, not harder
Exercise necessitates a huge increase in cardiac output (amount of blood pumped by the heart over a given amount of time), because of huge increases in oxygen demands. The muscle of the left ventricle is getting a workout, and that muscle can grow stronger with regular exercise. Endurance athletes may increase their left ventricular muscle mass by up to 30%! Essentially, the heart can do less work to pump the same amount of blood. This means that resting heart rate decreases.  This is desirable, since a high resting heart rate is an independent risk factor for cardiac mortality.
Natural vasodilation. Bigger, better vessels
As blood flow increases during exercise, mechanical stresses placed on the vessel walls are altered, and these mechanical stimuli prompt changes in the endothelial cells that line the vessels. Coronary artery disease and congestive heart failure patients who exercise increase their expression of eNOS (endothelial nitric oxide synthase), a key regulator of blood pressure. In healthy individuals, the eNOS effect is not as pronounced and is transient, but it stimulates angiogenesis and vascular remodeling, increasing both the number and diameter of arterial vessels in skeletal and cardiac muscle, which results in improved blood flow to these organs. [20, 21]
A few more favors exercise does for us:
Builds our antioxidant defenses. 
Enhances sleep. [22, 23]
Protects against chronic inflammation. 
Here’s the best part: if you exercise regularly, you will get better at it and start to like it.
Anything you practice on a regular basis will get easier over time, and the same is true for exercise. At first, it may feel cumbersome and very uncomfortable, but over time exercise will become enjoyable. Your body and mind will both thank you.
1. Bassuk, S.S. and J.E. Manson, Epidemiological evidence for the role of physical activity in reducing risk of type 2 diabetes and cardiovascular disease. J Appl Physiol, 2005. 99(3): p. 1193-204.
2. American Institute for Cancer Research: The Exercise Factor. [cited 2010 September 1, 2010]; Newsletter 85, Fall 2004:[Available from: http://www.aicr.org/site/News2?page=NewsArticle&id=7651&news_iv_ctrl=0&abbr=pub_.
3. The Price of Inactivity. American Heart Association.
4. Medina, J., brain rules. 2008, Seattle, WA: Pear Press.
5. van Uffelen, J.G., et al., Occupational sitting and health risks: a systematic review. Am J Prev Med, 2010. 39(4): p. 379-88.
6. Hyman, M., The UltraMind Solution2009, New York, NY: Scribner.
7. Gill, A., R. Womack, and S. Safranek, Clinical Inquiries: Does exercise alleviate symptoms of depression? J Fam Pract, 2010. 59(9): p. 530-1.
8. Uebelacker, L.A., et al., Hatha yoga for depression: critical review of the evidence for efficacy, plausible mechanisms of action, and directions for future research. J Psychiatr Pract, 2010. 16(1): p. 22-33.
9. Saeed, S.A., D.J. Antonacci, and R.M. Bloch, Exercise, yoga, and meditation for depressive and anxiety disorders. Am Fam Physician, 2010. 81(8): p. 981-6.
10. Ma, Q., Beneficial effects of moderate voluntary physical exercise and its biological mechanisms on brain health. Neurosci Bull, 2008. 24(4): p. 265-70.
11. Erickson, K.I., et al., Physical activity predicts gray matter volume in late adulthood: the Cardiovascular Health Study. Neurology, 2010. 75(16): p. 1415-22.
12. Davis, J.C., et al., Sustained Cognitive and Economic Benefits of Resistance Training Among Community- Dwelling Senior Women: A 1-Year Follow-up Study of the Brain Power Study. Arch Intern Med, 2010. 170(22): p. 2036-8.
13. Killingsworth, M.A. and D.T. Gilbert, A wandering mind is an unhappy mind. Science, 2010. 330(6006): p. 932.
14. Tierney, J. When the Mind Wanders, Happiness Also Strays. The New York Times, 2010.
15. Anderson, D.E., J.D. McNeely, and B.G. Windham, Regular slow-breathing exercise effects on blood pressure and breathing patterns at rest. J Hum Hypertens, 2010. 24(12): p. 807-13.
16. Brown, R.P. and P.L. Gerbarg, Yoga breathing, meditation, and longevity. Ann N Y Acad Sci, 2009. 1172: p. 54-62.
17. Ross, A. and S. Thomas, The health benefits of yoga and exercise: a review of comparison studies. J Altern Complement Med, 2010. 16(1): p. 3-12.
18. Duncker, D.J. and R.J. Bache, Regulation of coronary blood flow during exercise. Physiol Rev, 2008. 88(3): p. 1009-86.
19. Verrier, R.L. and A. Tan, Heart rate, autonomic markers, and cardiac mortality. Heart Rhythm, 2009. 6(11 Suppl): p. S68-75.
20. Kojda, G. and R. Hambrecht, Molecular mechanisms of vascular adaptations to exercise. Physical activity as an effective antioxidant therapy? Cardiovasc Res, 2005. 67(2): p. 187-97.
21. Brown, M.D., Exercise and coronary vascular remodelling in the healthy heart. Exp Physiol, 2003. 88(5): p. 645-58.
22. Atkinson, G. and D. Davenne, Relationships between sleep, physical activity and human health. Physiol Behav, 2007. 90(2-3): p. 229-35.
23. Montgomery, P. and J. Dennis, Physical exercise for sleep problems in adults aged 60+. Cochrane Database Syst Rev, 2002(4): p. CD003404.
24. Mathur, N. and B.K. Pedersen, Exercise as a mean to control low-grade systemic inflammation. Mediators Inflamm, 2008. 2008: p. 109502.