I have alternately good/bad self-discipline, and I can't always figure out whether I'll stick to some decision I've made, or if I'll even remember it.
I've figured out a good way to make me think of my commitments seriously. I've learned to take written contracts seriously and to the letter. So if I decide some form of action or behaviour is needed, and I decide that it's possible to keep up such action yet I'm bound to change opinions about it, I write a written "contract" for myself what to do.
I just decided that I am able to devote 40hrs/week to work and equal amount to personal development. So I wrote down my decision, defined "work" and "development" and decided planned and unplanned time for each of them.
I styled my decision in the form of employment contract to keep it memorable
I've heard that other people tell about their decisions to everyone to put social pressure on them to keep them.
Others just decide what they do and then do it, others dont decide and they just do what they do. Still others start by making an investment towards the promise, i.e. they buy a gym card for 2 years, so they have invested for their future health.
What do you do to keep promises for yourself?