I found Dr. Mirkin’s newsletter both informational and inspirational. Gets me back to exercising when I feel like slacking, and reinforces how important it is to keep pushing.
“I think everyone should have a regular exercise program, and it is never too late to start. See How to Start an Exercise Program. Do not start an intense exercise program until you have spent several months exercising at a casual pace.
Socialization usually improves the length of time, intensity and enjoyment of exercise, so it is best to join a group, exercise with your mate, or do your exercise regularly with friends.”
http://www.drmirkin.com/fitness/you-cant-be-too-fit.html
Dr. Mirkin is evidence-based, backs up everything with the relevant article/research and walks the talk by exercising heavily at an advanced age.