What studies say the number one best way to start an exercise habit is to give yourself a reward that you genuinely enjoy.
If you want to do something that requires willpower - like going for a run after work - you have to conserve your willpower muscle during the day.
If you believe you can change - if you make it a habit - the change becomes real.
Since the 17th century, insurance agents have been the foremost experts on risk.
For a habit to stay changed, people must believe change is possible.
Once people learned how to believe in something, that skill started spilling over to other parts of their lives, until they started believing they could change. Belief was the ingredient that made a reworked habit loop into a permanent behavior.