If only this stuff were as easy to apply as it is to understand.
Here's a quick summary: 1) Be specific. I'm not a bad person. I just made a mistake. 2) Notice the tendency to think of a negative outcome as more likely than a positive one. 3) Notice the tendency to take responsibility or blame yourself for things that could possibly be someone else's fault. The book includes a word of caution about blaming others. The idea isn't to shirk self-responsibility, it's just to notice and reframe the knee-jerk habit of always blaming oneself for life's problems.
I'm not doing justice to this small, powerful book. Some of the examples were a bit obvious, but the premise is sound and I found it helpful. It includes a link to an on-line test to take before reading the book. I scored miserably poorly on that test. Major pessimism. The book raised my awareness to unhealthy thinking habits and gave me better solutions.