If you do not start you will procrastinate and then you can't do anything. If you really want to start something then you have to start in anyway, if you take big steps at a time the chances are more that you will fall down suddenly. So that take small steps to achieve big thing in your life.
When you constantly go through step by step method to achive your goals, you are more likely to learn everything that occurs in a way, then whenever you fall down you will be self Comfident that you can go through the steps that you already gone and achive it again.
If you want to form a habit but it takes more effort. Then you need to divide it in small parts like start as a small piece somewhat if you want to exercise don't force for more reps do I as you think which is enough for you.
I hope you have understood what I want say in this post if you any queries you can comment below..