35% is a pretty decent discount for a book that could change your life.
Wim Hof, The Iceman, is a well known dutch extreme athlete who has changed the way science views the control we have over our autonomic nervous system through his feats. Rather than be the exception to the rule, he has taught many people to have the same level of control over their immune system responses, heart rate, skin temperature and many more autonomic nervous system functions previously thought to not be under conscious control.
The book goes into detail the studies done and the methods to get the results he has had.
I discovered Wim at the start of the year through a guided breathing meditation video on youtube and the path I've gone on since has been very positive for me with many positive changes.
I really recommend people try the guided breathing meditation video, it takes just ~10 minutes to do and can make you feel better the whole day. https://www.youtube.com/watch?v=tybOi4hjZFQ