I think there's a huge negative cycle when you can't find clothes that fit. Personally, if I feel like I look good, it does wonders for my mood. If I look good and feel good, I'll do more stuff, go out more, and be motivated to take care of myself. If I feel frumpy, OTOH, I'll get really depressed and have a hard time getting moving at all. I was heavier a year ago, and it really did wonders for me when I found decent larger size clothing at Target and a plus-size store that carried clubwear and other flattering clothes.