As I have become older I have developed a better understanding of the value of getting comfortable being uncomfortable. Geoff Thompson writes quite a bit about this idea and how personal growth can be harnessed through tapping into areas of life that you find difficult. For me, trying to acquire the basics of bjj and leaving my ego at the door is a big challenge. Any sort of uphill cycling on a bike for 2/3 hours will also do the trick.
Very interesting thread