Ask HN: What are your favorite techniques for overcoming the “pain” of learning?

I've accomplished many things throughout my career, and yet I still find it very painful and overwhelming at times to learn new subjects. When I'm reading a book on a difficult subject, I have a nagging little voice which seems to say "you'll never retain this" or "is this finally the subject that's just too much for you?" and other little seeds of doubt.

This is just noise, and I've proven that to myself over the years, but it still affects me every...single...time.

Two questions for HN:

  1. What are your favorite methods of overcoming this doubt? 
  2. What books (or other resources) would you consider helpful in this regard?

Thanks very much in advance.