I reward myself with craft supplies, musical theatre tickets, and plants. I'm a bit too nervous to buy clothes right now, since I'm still dropping weight, though I did end up buying two tops at thrift stores. Also, when I reached my 1/2 way mark, I bought myself a set of earrings that I've been wanting - nothing fancy, just sterling silver so they won't turn my ears green after a shower
As far as motivation for exercising, I find that the worst part for me is putting on my gym shoes. Once I finally get my tennies on and double-knotted (geez, what a lot of work!

), I'm typically too lazy to take them off. So then, I might as well work out. I take a good book with me if I bike - which helps pass the time, too. Also, what kind of workouts are you doing? I did the C25K, but can't say I enjoyed it, though I did complete it. I'm more of a dancer, so I've got loads of dance party videos that truly do make working out enjoyable.
You could also try lifting weights during the commercials of your favorite shows, or doing jumping jacks, lunges, or squats during commercials. Just a thought.