Switching from car commuting to bicycle commuting (and eating smarter) has done wonders for my health, including losing 60 pounds, controlling my blood pressure, and keeping me off of cholesterol medicine. I have experienced exactly the effect the OP described. I am in the best shape I have been in since the 1980's. My doctor and my family are huge cheerleaders for my continued bicycling. It has changed my life for the better in so many ways, and I don't plan to ever go back.