Lists of why exercise is beneficial

                          Top 10 Reasons to Exercise Regularly (Besides Losing Weight)
10. You'll Improve Your Memory
  9.You'll Have Better Posture  
  8. You'll Boost Your Confidence
  7. You'll De-Stress
  6. You'll sleep better
  5. You'll have more energy
  4. Better sex
  3. Sick less often
  2. Longer life
  1. More happiness

source:
Top 10 Reasons to Exercise Regularly (Besides Losing Weight)

source: 

http://darebee.com/motivation/50-reasons-to-exercise.html

25 Reasons to Exercise

1.  Strengthens heart muscle.
2. Decreases the incidence of heart attack.
3. Reduces risks for heart disease, e.g., reduces bad LDL cholesterol and increases good HDL cholesterol.
4. Improves circulation and oxygen/nutrient transport throughout the body.
5. Helps lose weight and keep it off.
6. Improves breathing efficiency.
7. Strengthens & tones muscles and improves appearance.
8. Helps prevent back problems and back pain.
9. Improves posture.
10. Strengthens bones and helps reduce risk of osteoporosis.
11. Strengthens the tissues around the joints and reduces joint discomfort and arthritis if appropriate exercise is selected and properly performed.
12. Decreases risk for several types of cancer.
13. Improves immune function which decreases risk for infectious diseases.
14. Maintains physical and mental functions throughout the second half of life.
15. Increases self-confidence and self-esteem.
16. Boosts energy and increases productivity.
17. Improves sleep.
18. Helps create a positive attitude about life.
19. Reduces anxiety and depression.
20. Increases resistance to fatigue.
21. May lengthen lifespan.
22. Reduces blood pressure.
23. Decreases the incidence of Type 2 diabetes.
24. Reduces stress.
25. Improves cognitive function.