Sometimes on this site, I recommend books, courses or other things I find worthwhile or have greatly helped me. These are affiliate links, and for books they go to Amazon for which I am an Amazon affiliate. It costs you nothing. I am required by law to let you know that this site might get a small pittance for you clicking on a link you see here and buying through Amazon, since I am an affiliate.
And just so I am compliant with things all legal and stuff, I have borrowed these images from the great Tim Ferriss. (Illustrations courtesy of Louis Gray and Jeannine Schafer).