The reason Wim Hof started doing his breathe work and cold plunging was because of anxiety and depression after his wife committed suicide.Wim Hof is a good example of doing extraordinary things with meditation and breathing techniques. Of course, what he accomplishes and dealing with anxiety and depression are completely different issues, but just the first example I thought of.
Cold plunging and Wim Hof breathe work are part of my daily routine.