I'm very new with lucid dreaming, and I run into a problem when trying to get what I want in dreams, if I become lucid. Let's say I'm on a bridge, and it starts to collapse. If I tell it to stop, and it begins to do so, I end up doubting myself(i.e: "What if the bridge doesn't stop? What do I do? D:") and then the bridge continues to fall because I don't truly believe what I said is final.

I'm afraid I doubt myself just as frequently in the waking world. I'd like to know how to boost the confidence in myself, at least in the dream world.