Some people just have a natural talent for it for those don't we just need to keep practicing. It took me about a week to learn back hops on a full suspension xc bike. Then I was just learning to roll obstacles like rocks and small walls, you don't have to hop on everything. Then the more complicated moves come in like pedal ups, pedal kicks, roll ups (zap taps) had them in a few months its all about rythem (what she said). If you just clear your mind of random things that might put you off you will get it I normally tried to ride three times perfectly to get it right.