Two things:
Pain and a sincere desire to be a better person.
I agree with you....being dissatisfied with who one is or what he/she has become is a big motivator.
Chucking false beliefs and letting go of the need to control outcomes and micro-manage the process also with the misery it creates is on my list.
Taking a good look, truthful, honest look at myself was the catalyst. Being unsatisfied with who I was or who I had become....