Only one problem. I'm 75 and because of a neck injury can't run anymore and I don't do pushups either. How do you do a beginning measure for someone like me who doesn't fit your 20 something mold.

I need to be in better shape than I am, but using the criteria of how many pushups and how far I can run will not work for me. What are some other ways to do the same thing. I used to run before my neck and upper back problems, but cannot do that anymore. I can walk and do try to park a ways away from stores and walk other places. I never was any good at push ups and probably could not or should not do them at all now. Suggestions?