I've been paying a lot of pool by myself lately because I want to get good and feel confident to play someone. After about a week of playing by myself I finally invited some buddies over and played them. I barely beat them and I even lost sometimes. As friends should do they all fooled with me saying oh wow all that practice and we're still able to beat you. When they left I decided to rack up and practice by myself again, I was back to my normal form sinking shots that I expect to make instead of missing rather easy shots, I then realized that my friends didn't beat me but the mental game in my head did.

How do you keep a composure to feel at ease and collected when competing against others?