Great article but I think it's a fine line. I am so much more productive when I am doing something I enjoy.

Let's say I am 5 times faster working on what I love to do, but it's only 50% as effective for my business as what I should do. Well it's still better than being 5 times slower to do something that's only twice as important.

The hard part is working out those numbers and knowing what wins, but being aware of the concept is a great start.