This is a harder problem than you seem to imply. There are very few physical activities I truly enjoy and these tend to require a significant investment of time and money (like skiing) and are not sustainable on any schedule that makes them useful as regular exercise. There are activities that I enjoy occasionally (hiking, running), but I feel like if I started doing them on schedule (I tried), the way I go to the gym, they would become a lot less enjoyable, because it is now a chore rather than entertainment. So I would rather go to the gym and hate it than grow to hate the things I actually like.
