4. Visit the doctor less. It's not only apples that can keep the doctor away. Active people are less likely to develop colon cancer. And ladies, women who regularly engage in intense workouts like running can reduce their risk of breast cancer by up to 30 percent.
5. Eat more carbs. Who doesn't love a pasta dinner? Now there's an excuse to slurp up more spaghetti. During intense training like preparing for a race (sorry, channel surfing doesn't count) increasing carb intake might help running performance and boost mood during harder runs.
6. Keep it interesting. Forget boring laps around a track. Interval training helps boost metabolism and rev cardiovascular fitness. Bonus: Research shows runners who do intervals have more fun while running (really!) and might be more likely to keep it up.
7. Live longer. Who doesn't want to live forever? Not only do runners have fewer disabilities and remain active longer than their sedentary counterparts, they actually live longer. And even as weekly running times decrease with age, the healthy benefits keep on ticking.
8. Get primal. Turns out Bruce Springsteen was right after all: Baby, we were born to run. It's what turned us from apes to humans and was used by our ancestors to outrun prey over long distances.
9. Slip into skinny jeans. Running is one of the best calorie burners out there. For a 160-lb person it can burn more than 850 calories an hour. Not like we're counting or anything.
10. Bring sexy back. Not only can having a rockin' runner's bod boost confidence in bed, regular exercise will help flexibility between the sheets — and get you in the mood more often.
11. Boost memory. Exercise has been shown to help keep the mind sharp and could even reduce symptoms of dementia. Hitting the track might also protect the brain against Alzheimer's, even among those with a family history of it.
12. See the sunny side. Active folks see the glass as half full not only while they exercise, but for up to twice as long after hanging up their kicks than their less mobile counterparts. Talk about "Happy Feet!"
13. Get a natural glow. Believe it or not, working up a sweat can rid the face of gunk that clogs pores and leads to breakouts. A solid sweat session can also boost natural oils, keeping things fresh and healthy. (Just remember to remove makeup pre-workout and wash gently afterward to avoid breakouts.)
14. Improve self-esteem. Need one more excuse to go green? Runners who ran outside and snagged a good view of nature showed increased self-esteem post-workout than those who had only unpleasant scenes to gaze at.
15. Stay steady. Older runners can keep their balance better than non-runners, protecting their knees and tendons in the process. Take that, yoga! Be careful not to overdo it, though: Too muchexercise can lead to stress injuries and bone loss.
16. Turn down the pressure. Running is a natural way to keep high blood pressure at bay — and fast. Amping up workouts can help lower blood pressure in just a few weeks.
17. Build stronger bones. Resistance training is awesome, but word on the street is that running might help produce even stronger bones than cranking out reps. As an impact exercise, running helps build the muscle that lower-impact workouts ignore, keeping bones healthier even as they age.
18. Get an energy boost. Feeling sluggish? Try going for a run instead. Just one running sesh can increase energy and chip away at fatigue.
19. Bring the furry friends. Dogs are man's best friend for a reason — but they can also be man's best workout partner, too. When it's time to hit the trail, grab a leash to give your pet a new kind of treat.
20. Carve that core. A strong core improves posture, strengthens limbs, and helps make everyday activities a breeze. And whether we feel it or not, running engages that midsection, strengthening those all-important muscles. Bonus: A solid core in runners can improve performance, too.
21. Sleep better. Runners tend to adapt to set sleeping routines in order to keep running performance high. Even better: Running also encourages higher quality sleep, which translates into better Zzz's all night long.
Go to Greatist.com for the full list of 30 reasons.
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- Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state. Achten, J, Halson, SL, Moseley, L, et al. Human Perfromance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, B15 2TT Birmingham, United Kingdom. Journal of Applied Physiology, 2004 Apr;96(4):1331-40. Epub 2003 Dec 5. 
- High-intensity interval running is perceived to be more enjoyable than moderate-intensity continuous exercise: implications for exercise adherence. Bartlett, JD, Close, GL, MacLaren, DP, et al. Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. Journal of Sports Sciences, 2011 Mar;29(6):547-53. 
- Reduced disability and mortality among aging runners: a 21-year longitudinal study. Chakravarty, EF, Hubert, HB, Lingala, VB, et al. Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, California, USA. Archives of Internal Medicine, 2008 Aug 11;168(15):1638-46. 
- Physical exercise protects against Alzheimer's disease in 3xTg-AD mice. García-Mesa, Y, López-Ramos, JC, Giménez-Llort, L, et al. Institute of Biomedical Research of Barcelona (IIBB), CSIC-IDIBAPS, Barcelona, Spain. Journal of Alzheimer's Disease, 2011;24(3):421-54. 
- Cognitive function in elderly marathon runners: cross-sectional data from the marathon trial (APSOEM). Winker, R, Lukas, I, Perkmann, T, et al. Unit of Occupational Medicine, Medical University of Vienna, Vienna, Austria. Wien Klin Wochenschr, 2010 Dec;122(23-24):704-16. Epub 2010 Nov 15. 
- Long-term effects of aerobic exercise on psychological outcomes. DiLorenzo, TM, Bargman, EP, Stucky-Ropp, R, et al. Department of Psychology, University of Missouri-Columbia. Columbia, MO. Preventive Medicine, 1999 Jan;28(1):75-85. 
- Exercisers achieve greater acute exercise-induced mood enhancement than nonexercisers. Hoffman, MD, Hoffman, DR. Department of Physical Medicine & Rehabilitation, Sacramento VA Medical Center, Mather, CA. Archives of Physical Medicine and Rehabilitation, 2008 Feb;89(2):358-63. 
- The mental and physical health outcomes of green exercise. Pretty, J, Peacock, J, Sellens, M, et al. Department of Biological Sciences, University of Essex, Colchester, UK. International Journal of Environmental Health Research, 2005 Oct;15(5):319-37. 
- Age-related degeneration in leg-extensor muscle-tendon units decreases recovery performance after a forward fall: compensation with running experience. Karamanidis, K, Arampatzis, A. Institute of Biomechanics and Orthopaedics, German Sport University of Cologne, Carl-Diem-Weg 6, 50933 Cologne, Germany. European Journal of Applied Physiology, 2007 Jan;99(1):73-85. Epub 2006 Oct 25. 
- Exercisers achieve greater acute exercise-induced mood enhancement than nonexercisers. Hoffman, MD, Hoffman, DR. Department of Physical Medicine & Rehabilitation, Sacramento VA Medical Center, Mather, CA. Archives of Physical Medicine and Rehabilitation, 2008 Feb;89(2):358-63.