When boiled down, self-discipline is really a function of trust.
The most disciplined are the ones who make and keep the most promises to themselves and the least disciplined are the ones who make and break the most promises to themselves.
If you seriously want to become disciplined, then you need to prove it by taking yourself—the promises you make to yourself—more seriously.
If you’re already a notorious self-promise breaker… then become keenly aware of this and stop promising yourself more than you can deliver.
Just as under-promise, over deliver is a great strategy for a successful business, so too is it a great strategy for becoming self-disciplined. And marginally increasing the seriousness of your promises as trust (in yourself) is restored is how self-discipline is increased/built.
And take note: as is true with other relationships in life, trust is built slowly, but can be broken rapidly. So be patient, take “marginally” seriously, and build discipline as you would a brick wall—one brick (one promise) at a time.
P.s. I also published: 25 Lessons From 1,000 Days Of Daily Writing on Medium.