When I'm walking fast (3.5-4mph) for over 20 mins, I sometimes feel like I'm in a completely new place, even in the same neighborhood I've walked for years. My senses are heightened and everything seems brighter even on a gloomy day.
If I am dreading my work out, I stop thinking about it and just do it! I get up and I go to the gym or I get up and get on my step aerobic bench. If I think about how much I don't want to do it too long I'll make up excuses for reasons to procrastinate or not go!