Mortify means to kill off by degree. Think of paying a mort-gage and you get the idea. The way you settle a mortgage is by making a series of small payments over a string of years. That’s mortification. You kill off that old, duplicitous self by degrees, not all at once. Johannes Tauler, a Twelfth Century German theologian and mystic wrote:
"This dying has many degrees...A man might die a thousand deaths in one day and find at once a joyful life corresponding to each of them."
Mortification is a series of transactions we make all our life, it's a cycle of successive and small surrenders. I give a little and grow a little. That's how we die. Bit by bit.