Join some cool game project to get motivated again! f.e. Tremolous is currently getting a massive graphical update in the form of TremZ (no website yet, talk with them on IRC: tremz on freenode) and I think they would be happy to have a skilled texture artist and props modeler like you.

I know how you feel. Have you heard of light therapy already? http://en.wikipedia.org/wiki/Light_therapy

I think that could help you.