The nice thing about running is that you can pack a decent amount of exercise into a relatively brief period of time, and at least you're outside. Gyms feel like gerbil wheels to me.
What I really love to do is ride my bike, but that takes more time and better conditions.
BUT, I try not to control it too much, every time I start to focus about something else[2], I feel like flying. The minute I start thinking back about my body, the pleasure vanish.
My goal is to tighten my sensitivity to these two ideas so I can reach flow faster and longer.
[1] except min 5 and 15 where I often crack down a bit, maybe the body shifting sugar supplies.
[2] a rant, a fantasy, a job idea, some music...
I can't say that running itself is fun for me, but the extra hours of Hardcore History I've listened to while exercising have made the process much more tolerable.