iMobility exercises and Mastery

I do the foundation, and it happens to me that i could do the Mastery in one exercise, but his iMobility 

exercise is hard for me and i can't do it properly.

 

What sholuld I do in this situation?

 

ty.

Work hard to get your mobility up to par

Don't move on to the next exercise until you've mastered *both* the strength and mobility elements.