Having read "The Way of Aikido" three times, I was eager to read "Mastery", but had to wait for it to come into stock. Having obtained it, I read it twice in fairly quick succession, and can say that it was without doubt worth the wait!
Rather than being of the super-enthusiastic change-your-life-in-a-flash genre, this book carefully analyses the steps required to achieve any specific goal, realistically analyses the reasons why goals are so often not achieved, and emphasises the need for long term commitment to learning and practice.
I am especially drawn to the author's emphasis on enjoying the journey as much as the destination, and his observation that the most boring thing of all is to be constantly searching for novelty and superficial stimulation.
This is a deeply satisfying book, and an excellent companion to "The Way of Aikido".