Quite simply that it’s all up to them! I tell them that I should be considered their “guide,” but that it is them who has to make the trip. Their motivation to start, or to continue has to come from within themselves and can’t be extrinsically motivated if it’s to succeed or last. Usually, this is enough to jolt them into reality and either continue to move forward or to stop until they find that “inner” strength and motivation.
I hope that this helps.