One good reason death to self, being last, self-sacrifice, and carrying ones cross; can all be symbolized by crucifixion..is because crucifixion is to the body, what self denial is to the ego.
We will do anything before choosing to crush/insult ego. It is the most “excruciating” thing. We will even firmly believe our own reasonings and justifications in order to keep from putting that beast underfoot.
The Undoing of Me 