I always thought I could make big changes all at once. Against all advice. Why? Because, unlike all other mortals, I have an iron will and iron self-discipline. Because I am I. Did it work? Hardly ever. Why? Because soon that big motivation is eroded by the sheer magnitude of the task, by the difficulties, by everyday necessities that have to be taken care of, by lacking the necessary resources and skills required.
If you think you are different, good luck, prove me wrong, not once, consistently. Otherwise, do it like every master does it: take consistent, small manageable steps. Be gentle on yourself, even if you are a tough guy like me. And never give up. And if you do, start again. And remember, it’s a process; you have to work on it, on yourself, your whole life long. Sooner or later, it will become a habit, not a chore.