Where do you run? I like to mix it up to keep it interesting. I started out on treadmill so I could stop when I wanted to stop and not have to come all the way back, but now that I have some stamina built up, I really enjoy outdoor running. I have to stick to road mostly right now, near home in the mornings before work, but love to hit a good mountain trail when I can get up there. Time just flies by when you're preoccupied with choosing a path around roots and rocks!