Lexicus
Deity
I would also caution against getting too fit.
Sometimes -especially if a bit but not too much alcohol is involved- you'll be able to run for hours which can be frustrating to you and the other party who will sometimes take it as a personal insult.
In my experience open and honest communication about these issues prevents anyone from getting offended. It can be hard to talk about that stuff but it's a lot easier than the alternative(s)...