It's frightening how much lifting can be "mind over matter" - one time I had a friend round for dinner and he was watching me bench beforehand, and I benhced more that night than ever before. Had my mate not been there, I would not have been able to bench the same weight.
Another time, more recently, I attempted a 1RM bench and failed. A few minutes later, after psyching myself up and doing some quick and light dumbbell flies, I nailed the bench no problem. It's all about confidence and believing in yourself.
