Practice. A verb and a noun. Nouns are boring, so…
Verb:
1. carry out, apply
2. to do or perform often, customarily, or habitually
3. to be professionally engaged in
4. to perform or work at repeatedly so as to become proficient
5. to train by repeated exercises
There are so many great words in there. “Apply, perform habitually, professionally engaged, repeatedly to become proficient, repeated exercises.”
I could give examples of how consistent, engaged practice can make a huge difference in performance. There are thousands of books on the subject. My most recent favorite is Mind Gym. I’m just going to keep it short and give a few reasons to get to every practice – even when you don’t feel like it. Other people can probably think of even more and hopefully will post them here.