I drive a lot, to the tune of about 2 hours a day pretty easily. I sometimes spend that time thinking and losing myself in some pretty negative loops. What I've been doing lately is putting on some stupidly loud music and then singing (badly) along to it. It's just a total release, even if the music is sad or reflective of some negative thoughts I'm having, just focusing on the music and not my self destructive thoughts really does help.

That and regular exercise. There is a clear 100% correlation with my moods and how regularly I've been working out. When I start missing workouts or have gaps in my exercise I can clearly feel my mood decline.