Whether it be to do your job, get your schoolwork done, clean your house, work on your creative passion, etc.
Bonus points if you’re someone without reasonable self-control so saying something like “I can only have a cookie after I do this/while I do this” doesn’t work for you and you’re just going to eat the cookie and not do it.
You build discipline so as not to rely on motivation, as motivation is unreliable.
Like, if you rely on motivation, depression will win. It’ll get ya. Sneak attack, pin you when you’re down. Or just heavy life events like losing a loved one, or a job. When shit hits hard, there is no motivation. None. Zero. Things can happen in life where purpose feels completely gone. You cannot rely on motivation, because if you end up here and motivation was your only path forward, you’re toast! Well not really, but the uphill battle is even steeper.
What are you trying to to be motivated to do? Play music? Every day, 30 minutes, no excuses.
Get into hiking shape? 1 small hike every weekend. Rain or shine.
Build the discipline. Form the habit. The motivation will come and go. Habits get broken. Discipline stays.
I mostly second this. I have a mantra “Embrace the uncomfortable”. Not in a “work yourself to death for some number” kind of way, but in a “go outside, even if its raining” kind of way. It helps me to appreciate small comforts afterwards and reduces the amount of energy needed to do stuff.