did a state championship road race a few years ago, thinking i could climb decently (having raced a few seasons already)...made it over the first small climb barely hanging onto the pack, and blew up spectacularly on the BIG climb that came up next. Chagrined, i decided to attack all the climbs on the group rides as hard as i could for the next couple of months, and was surprised to make gains fairly quickly. A big part of it was physiological (thinking i had to pace myself more than i really did), but definitely gained some fitness too. By the end of the summer I was in the top 3 up the more competitive climbs in a group of cat 3 and 4 racers.
being scared of cracking has been the biggest thing for me to overcome as a racer, and realizing that if i do crack, nothing really that bad happens, was the biggest difference. the brain is a powerful thing when directed correctly.