I have found in dreams and in real life that if I focus really hard on getting something to happen, it doesn't work. In the dreams, objects don't move, I don't fly. In real life, I get too caught up in the details and lose the overall goal and the lessons any problems are teaching me.
However, in my dreams and real life, if I make my intentions strong towards my goal, and let the method be determined by the environment, or the dream, I can and do succeed.