The Motivation Myth is two things: an outlook on what motivation really is and what "causes" it (how do you get motivated?), and a series of specific tactics to being successful.
The outlook is quite simple. Motivation is not the cause of working hard (thus, success). Success is the cause of motivation. As in, motivation just "is" — you can't motivate yourself. But you can design systems so that you're frequently successful, and motivation will result. As such, lofty goals may be useful, but should be discarded as soon as you have decided the path you'll actually do. For example, if you want to run a marathon and don't currently run, that is a lofty goal to work towards. But it's also far away, and difficult to have successes towards. Instead, with that goal, design how you'll get better a running ("run every morning for at least 1 mile, before 8am", etc), and then throw the goal away. Perhaps you will run a marathon, but your task every day is to do what you decided that you'd do.
The tactics fill most of the book, and span from losing weight, having professional mentors, starting a company, time management, giving praise to employees, etc. Overall, I'd say the tactics were good enough to keep me engaged, but many just didn't apply to me — or I had already implemented. The outlook (fully laid out in the first part of the book) was the most meaningful.
If this sounds interesting, start the book to get his outlook on motivation. He explains and justifies it well. Then consume as many of the tactics as you're interested in.