Initially, it was _weight control_ (I ended up dropping 30+ lbs. This process was not just exercise - it had to be paired with proper diet (otherwise, you don't see any lasting results or you end up flattening out in your weight loss graph).
After I got to my target weight, it started getting kind of boring. But then, the thing that really did it for me, was getting into surfing. I love surfing, and do it multiple times every week. This is not exercise - it is just pure fun. However, you end up getting tired after paddling for sometime. The purpose of the gym changed for me. It was about improving my surfing. Squads, cardio, push-ups, lifting weights become just a way for me to improve my pop-ups, paddling endurance, etc.
As a nice side-effect, I sleep better than ever before. Would definitely recommend it :)