I've just started getting back into lucid dreaming and I'm using a free course to help me get back into it.

Anyway, sometime early this week, I had two(!) lucid dreams. Though the lucidity didn't last long, it was enough to get me hungry for lucid dreams again.

In one of the dreams though, I flew up and to the ceiling and, though I've found it very easy to pass through walls and ceilings before, I wasn't able to do it this time, no matter how much I said I could, no matter how hard I pushed, no matter how kindly (or angrily) I asked it to let me pass and a DC behind me actually laughed at me for being unable to do something so simple. Eventually, I gave up and went out the front door. I tried to fly but found myself floating back down to the ground again, slowly at first, and then I plummeted and wasn't able to jump higher than a few feet.

Does anyone have any tips for how to get through this or how to avoid it happening again? Am I just hideously out of practice?