Walking. They say it's a good exercise and healthier than driving everywhere like some people seem to do.
I enjoy going for walks around my city when I have free time or on weekends. If I'm not in a rush to go somewhere that's less than a 30 minute walk away from where I'm at at the moment, I'll just walk.
This makes me sound like a tourist, I suppose, but there's something fun about just walking around a big city. And it's probably better for your well being than just sitting on your ass at home in front of your computer all day, anyway.
How often do you walk? Are you the type of person who takes your car literally everywhere? I know people who will take their car even to a supermarket that's a 15 minute walk away and they're just going to buy a couple of small items. I understand if you're in a rush or busy, but if not, it's best just to walk, imo. I think it's just faster to go there by foot since you don't have to spend a long time looking for a parking place which might be far from said place... and requires you to do a rather long walk from your car to the place you're going to
It's funny. I like walking a lot, but seriously dislike running.