I have been running and lifting weights since 1973 (I stopped running in my late 30's). I now do cardio (elliptical machine), stretching and weights three times weekly. I weigh what I did in high school and in general am fit as a fiddle (with the minor exception of Parkinson's of course) . . . It is always hard to begin a serious fitness program but I cannot recommend it highly enough!
Burden
It takes time and energy to run off to the gym - but once I have done so, I never regret it!