I've just accepted it's my personality type and I jump around hobbies. People are built different, I'm sure the people who can focus 1000 hours on a hobby have other things they wish they did different. Embrace yourself and how your brain works when it comes to your leisure time.

That being said if I have something I want to focus on for self-growth/productivity reasons I use bullet journaling to hold myself accountable and stay on track. It's helped a lot.