I wish you well in all efforts to think happier thoughts, Sisabel. You often read in the therapeutic literature that feelings follow thoughts.
Personally I've had the best luck with trying not to think at all! (lol) (Naturally there will be exceptions, as sometimes you'll have to think your way through logistical situations, and of course you're going to have feelings, which you pretty much can't get rid of other than to distract yourself. You end up having to abide with them much of the time, uncomfortable though they may be.
I work between and around these challenges myself, every day, every hour, every minute. I wish us both well in trying to heal from the constant messages that we're of little value.