how to animate movement which you don't know about?

hey guys, i basically wan to know how you guys animate a character moment about which you have no idea about as to how that will go on and work … i know many of you like record yourself doing the action and then use that video as a reference but there are few things you just cant record yourself doing … so what your plan to tackle that scenario
thank you

What movement are you trying to animate? Perhaps dont try animating it at all and find a ready-made sequence?

I just use my imagination and hope for the best.