Lucid Dreaming

I'm not sure how to achieve the actual state of lucidity, but once I realize I'm at that moment, I can have a usual decent control over my dream. ie- Flying around, changing things, etc.

I found that if a certain thing happened that day, or major things you've been thinking about, usually affect the state of your dreams.

>>20
My "product of imagination" started to cry. Fun.

All my last lucid dreams after some minutes became foggy, all becomes grey, my body becomes heavy, i fell on the ground and then sometimes I wake up, for the rest I do not remember. How do I get rid of that?