Self Discipline: Why? How?

I am growing. Even if I don't see the results, I know somehow I am growing. I know this because I put myself in uncomfortable positions. These situations force my hand to change my perspective.

But what about when I do put myself out there? How do I change then?

I don't know how to become motivated for myself. Self discipline is such foreign concept to me.

People who can just tell themselves to do something and their mind just does it. WTF is that? And can I have that in my brain please?

I have to force myself to grow and I have to force myself to reflect on my behaviors.

But self discipline is an action I have to take that doesn't make sense to me.

I hope that I can learn more about my brain trauma and why I respond the way I do to life.

But until then

Why can't I self discipline?

How do I self discipline?

and if I can't learn or change my behavior will I fail at life?