I skied when I was young and later rollerbladed on ramps and street and did adult gymnastics classes for fun. Definitely learned to roll out of a crash and body awareness in the air. You just get used to rolling instead of trying to stop yourself.

I used to ride a racing bike to work and had to slam the brakes on suddenly once when an idiot in a car suddenly turned in front of me. I went over the handlebars, but instinctively did a forward somersault/roll and was pretty much unhurt except a slight graze. It happened so fast that I have no idea how I did it. In the air I must have recognized that my body was spinning and I just tucked into it until I was the right way up again.

So I think the answer is just practice. Do silly shit until you learn how to land it. A foam pit makes it less painful. :-)