I'll start first.
Breakthrough #1: Focusing just on one thing. Back then it was SEO for me. It doesn't matter what you focus on as long as you focus just on that one thing.
Breakthrough #2: Getting a mentor. I got a guy that was making 10 times more money. He opened my eyes and expanded my thinking. Back then I was making more than most professionals, but he asked me "Matt, why are you playing small?". What a moment!
Breakthrough #3: Going to a 10,000 GBP seminar, hanging out with super successful guys. I realized they aren't smarter or better, they just took more action and they work HARD.