First of all
Second, what do you mean you could never have lost the weight without surgery? Sure, it played a part in getting down 200lbs, but it was YOU that got the weight down by making the choice to do something about it.
As for keeping a positive attitude: what makes you happy? For me it's writing or watching a movie (yup, I'm 90% sedentary!) and sometimes even running helps. Most of all, find some time to take a break from everything and do something for yourself. Buy a new outfit, get your nails done, go see your favourite team play or take a vacation. In other words, try not to dwell on the past and how you got to where you are and instead concentrate on making yourself happy.
(I hope this makes sense and helps