Hm. Good question. Well, my reasons have changed since starting my weight loss quest.
Before, exercise was something to be endured.. and the reasons for dieting were many and various, all related to a pitifully low self esteem.
Now, I still have days where I cry and decide not to go anywhere because I am too fat (laugh), they usually happen around the same itme every month.

But in the morning... I pinch my soft belly several times and kind of roll my eyes and think "Damnit, I have to get rid of this." Then I stretch my legs and rub the thighs and feel happy that they finally feel and look so good. Once I am actually out of bed and have downed the caffeine I love to work out. And if I don't, I do once I get into it. Weight training I always listen to music, but focus on the muscle. Cardio, I do it on a nearby mountain so the scenery is good enough, distraction and motivation.

OH! Lately, my biggest motivation was not wanting to go through the torture of weight training after not doing it for a while. Not the training, but the massive soreness for the following week.

Take care,
Meg