Yes, exercise is a winner for more than just your body. In addition, it doesn't have to be hard. It's hard to lever yourself out of the chair, we all know that, but it only has to be a 20 minute brisk stroll around the block to be doing you good in every way.
Edit: How about "If I go out 3 nights a week and have a brisk walk for half an hour then on Saturday I can have a pint/Steak and Chips/whatever takes your fancy"?
Edit: How about "If I go out 3 nights a week and have a brisk walk for half an hour then on Saturday I can have a pint/Steak and Chips/whatever takes your fancy"?