L2C,

Obviously you care for your friend and that's why you encourage him. 65 is not too old to change and sometimes there is just one thing that triggers a turnabout for people. Others who care about someone often are the little nagging voice in the background that helps a person come to that conclusion on their own.

So long is your urging is now and again and it's not taken the form of every time you see him you start in on him, then it's a sign of caring and not hounding. Not everyone is good enough friends or has the courage to continue to gently urge/nudge a person in a healthier direction. Bravo for being "that person."

I don't think you are strange for wanting to challenge yourself aggressivley to keep fit. People can have worse destructive habits like drinking, drugs, gambling etc for hobby's. So if a person gets passionate about living a healthy lifestyle, good for them!