It might not take as much exercise as you think to make a noticeable impact on your future health:
“Trading 2 minutes/hour of sedentary activity with light-intensity activity was linked to 33% lower mortality in the general population and 41% lower mortality in those with chronic kidney disease (CKD), according to an observational analysis ” – summary of a research study in Medscape Nurses. This site requires you to sign up, but it’s free and I’ve found it useful.
The study was published April 30 in the Clinical Journal of the American Society of Nephrology. Abstract Here.