Prime Ski Racing: Triumph of the Racer's Mind, by Dr. Jim Taylor (see on amazon).
A great book about the psychology of ski racing - in fact the book helps you understand and improve five areas of the psychological aspects of ski racing, including motivation, confidence, intensity, focus and emotions.
The goal of the book is to allow you to be the best you can be, so your racing is always 'prime', including self-assessment and corrections, evaluations etc.
It is applicable not only to skiing, but probably most action sports and life in general: highly recommended to anyone that hasn't stopped trying to improve, either racing something or not!
The author has a youtube channel and he talks about many of the points in the book in his podcasts: Prime Sport Alert!.