One of the most useful things I have ever done is this:

I would find a mentor. I offered my services to do whatever needed done. More often than not I learned useful skills through the doing. Skills that I needed for myself. And while I was around the mentor, I could learn from him.

Life needs a lot of skills to do life successfully. The opportunities to learn those skills is sparse… Because skills are not knowledge, even if they are mental, intellectual skills: they are the ability to do, to perform a skill… not to understand it.

To learn skills on your own stuff is very difficult. Why? Because you are too invested, you