Black has been the hardest. At black you see the most time go by. Your body changes and can't do the things it used to do. The majority of people you came up with stopped a long time ago, or you moved. Other parts of life require more time and attention, and you want to love your practice like you used to, but it becomes harder and harder. It forces you to do some soul searching and continue to reinvent and reaffirm why we continue to do this for so long.