When you come out with a complaint along the lines of "I've put on almost half a stone, I look like the female Michael Moore", or "They think I'm a headcase at work, they're going to fire me", there's normally some nice soul around who'll reassure you or tell you to stop exaggerating.
Instead of muttering "That's nice but it doesn't help", learn to ask other people to explain their compliments and to back up their criticisms. Note their thoughts down in a little notebook and consult them whenever you have a self-confidence crisis!