How did you become so good?

Play over the board with players stronger than you. I've recently started attending a club/tournaments and it really has made a difference. When you lose to a stronger player and are lucky enough to have them point out your mistakes you'll learn a lot. That kind of analysis is so much more powerful and memorable then flipping through your inaccuracies with Stockfish.

Played a lot of correspondance and tons against the computer. To reach the next level I need to start to play blindfold so I can picture how the board will look in 3-4 moves.

Play OTB chess

100 push-ups, 100 sit-ups, and lots of grape juice, every day!