I do it randomly in lucids when I am not thinking about. It just takes practice. You need belief, but you also need to imagine it happening as well (IMO). For me imagining flying is hard, and when I jump I know exactly what that feels like, so I know exactly when I should be coming down. It is annoying. Some things come easy to some and harder to others. Telekinesis is easy for me, fire is easy, flying is freaking hard. I pretty much have to jump out of a flying car to do it. :/

Practice, practice, practice. It is just fun to practice this because you are in an LD, so don't let it get to you!