Advice on loosening up in mtt's

[JoeBlazer55]

I play a few mtt's a week and I always find myself in the same situation: get about halfway thru the field but don't have enough chips to make any moves and end up pushing in with A5 and I'm out. I've tried to loosen up earlier in the tourney to build up my stack but I'm tight by nature and I can't always pull the trigger even when I know I should. Anyone who's been in the same situation: how did u overcome?

The guys with the big stacks at my table are always the ones who play weak hands and seem to hit huge with them. I guess I should stop waiting for good hands.