The secret seems to be: Practice. If you want to be able to do new things, you need to always be doing new things. I am always trying to learn something new - mentally and physically. For example, I am very right-side dominant in my body, but I have lately been trying to open more doors with my left hand, throw stuff at the trashcan with it, etc.
Always be doing at least one new thing in your life if you want to be doing new things for the rest of your life. It is OK to fail at a new thing! You just have to admit failure, pat yourself on the back for your courage, take stock of what went right and wrong, then pick a new new thing to do.
Relatedly, I have noticed that some people who I considered much smarter than me as a teenager often no longer appear to be, and I believe it is because they stopped trying to grow new types of skills and thus let their brains stagnate.
It is hard to do unfamiliar things, but so worth it.