I have just watched a Star Wars Movie for the first time so I dont excatly know how you can tell how strong someone is with in the force, lets use an example, like being strong enough to lift a walker off yourself(Darth Vader) without getting harmed, or strong enough to befriend a HUGE animal(Ezra)Anyone like to tell me so I dont have any spoilers? this is because i have barley enough time to watch the movies I it requires me ALOT of willpower.