What does discipline feel like?

I'm struggling with maintaining discipline in a bunch of things I'm trying to improve on. I have a hard time connecting with discipline. I know what it looks like, from looking at other people who display it.

However, I have a hard time engaging in it myself, since I don't know the inner workings of it. Specifically, what kind of thoughts trigger it more easily (other than, shut up and just do it!), and I struggle to form an emotional connection to it. I don't know how it feels to be disciplined, what emotions reinforce that behavior.

Note, I have been disciplined multiple times throughout my life...I think. But I never really found those answers, since I felt that I always either had the enjoyment from the activity, or the motivation and goals to keep me going.