About month ago I have a struggle with flying when I'm lucid, but I find a way to fly very easy and quick. First when you realize that you're dreaming and if your wish is to fly and you can't just look at your environment, e.g. if you want to fly on top of the tall building just imagine that building is shrinking and becoming smaller and smaller, in that moment have a thought that you want to fly there, feel like you going up and building become smaller...building will not shrink and you will not bee on the ground any more, when you detach from the ground it's easy to fly where you want. Principle is the same for every object you can see there, if you wanna fly to the sky use clouds or sun or stars.

I hope that this will help someone who have troubles with flying.
PS: Sry for grammar errors