I've been wanting to post on this thread, but have been unable to do so, simply because I can't put into words what I feel before a lift. I can tell you I don't operate on anger, and there are probably some religious aspects (yes, if you can believe) that go into the intensity of the situation.
Visualization is a must.
On the other hand, I would encourage you to see those times of internal doubt as a tool. When you walk up to that bar, and you don't feel like you're going to make it, and you lack drive, and you miss...think about what that brews inside you. Think about how that disappointment will move another barbell down the road. Sometimes you have to feel weak to appreciate, and revel in, the times you are strong, and seek those times out rather than letting them pass. One door closes, and another opens.