Malcolm Gladwell's book, Outliers promises if you put in about 10,000 hours or 10 years of practice, you'll become an expert. But I think most of the people misunderstood that statement.
If you do soccer, 10 years of practice will make you good at it. But it would be only to an acceptable level. You might be able to play in a regional league but not World Cup not even national league.
So what makes a world-class expert? One way is deliberate practice. You don't become an expert by merely repeating the same activities over and over. You must be selective about what to practice.
People like the idea of 10,000 hours rule and deliberate practice. It seems easy. As long as you do it every day with just a little patience every day, you become an expert in 10 years.
The inconvenient truth about deliberate practice, it is far from easy. You have to push the limit otherwise you will get stuck at good enough plateau. That is why most people will remain mediocre.
Deliberate practice is uncomfortable. To make matter worse, you have to do it every day. Will you torture yourself every day with painful activities?
Let say you are determined to be a writer. You aspire to write a book as a side project while maintaining a day job. I know for some people, writing is fun and enjoyable. But for most of us and professional writers, writing is hard.
Will you write after coming home when work already drained your energy? What work for me recently, I will do anything uncomfortable in the morning and get done with it as quick as possible. It must be short. It must get finished in a couple of hours. It is okay if I don't get productive after that.