The Finn has been with Chelsea since he was 16 in 2018.
He told chelseafc.com: "I’ve always enjoyed work.
"I’ve always enjoyed football. I enjoyed challenging myself and getting better. There is small stuff on the way that has stuck with me. I wanted to succeed. That time before I came here, all of my decisions were about what would help my football better. It was my way of thinking. I just wanted to become better.
"The next period is about working up the levels. There is a big pyramid. When you get near the top, there are so many good players. The differences are small, but they’re huge. It’s also about having a bit of luck and taking your opportunities.
"So far, football has been my life. It’s been the main focus, with the time I’ve spent on it. It’s not been a huge sacrifice in that way because I’ve wanted to play, but I’ve left other things behind."