I'm not a health nut, but I take care of myself. Not to brag and not to be vain, but my decisions are purely to avoid going to the hospital with something that could have been avoided. I exercise and eat right to be healthy. I don't spend the day thinking about what I shouldn't eat, I spend it thinking about living a long life and travelling with the girl of my dreams.
If you don't ever want to go into a gym, you can still get in fantastic shape. You can set aside time to go walking, play interactive games with your kids, go to the park and have a workout on the play structures and benches. That will get you healthy. Also consider trying yoga, pilates, or a sport with friends at your fitness level.