This is an excellent book. Also consider Behavioral Activation (see https://en.wikipedia.org/wiki/Behavioral_activation https://en.wikipedia.org/wiki/Behaviora

This is an excellent book. Also consider Behavioral Activation (see https://en.wikipedia.org/wiki/Behavioral_activation https://en.wikipedia.org/wiki/Behavioral_activation), which is a somewhat competing theory that essentially says that doing is what really matters and that what you're thinking is much less important. Just getting yourself to do things might be the key. Easier said than done, of course, and it's almost just a restatement of the procrastination problem.