I started lucid dreaming in my early twenties. It started because I wanted to remember more of my dreams. A friend advised me to say to myself as i was falling asleep, "tonight when I dream, I will remember to wake and record the dream"- like a little meditation. I kept a notebook beside the bed. After a week it started to happen and I would write down the dream and try to understand the meaning in the morning. Sometimes it was just gibberish, but in time I got better at remembering and writing something understandable.
I don't keep the journal anymore and find it very easy to influence the course of my dreams. Sometimes I decide to just end them, other times I will take an active part and react to events.
My favorite flying dream is to be an owl and fly at night around the farm I lived on as a child.