I don't want to do it

Most of the breakthroughs I’ve seen in my life were from seemingly unpleasant things I didn’t want to do, and yet I made myself do them. At times the reward comes right after, other times they don’t. But they accumulate and build up a tolerance for doing things I don’t want to do, and now I get motivated not because I initially wanted to do things, but because there’s fulfillment in the simple achievement of getting unpleasant things done. It’s like a game where I constantly beat the version of myself that don’t want to do things.