OK, so I'm fully aware that there is a bit of revisionist history going on here, but I'd like to claim that among the early ascetics, those who got it right were the ones who saw that the way to spiritual maturity was not to transcend (or mortify) their flesh, but to transform their flesh. And the transformation process is one of reprogramming.
Let's take fasting as an example. I used to think that fasting was some means of bribing God (like people who go on hunger strikes to protest various causes). I want God to do something really bad, so I'll quit eating to show him how serious I am. And I don't want to discount the "fast and pray" injunctions and the relation between the two.
But my understanding of the practice of fasting has been transformed by the model of flesh and spirit I've been propounding. On this model, fasting is like doing spiritual calisthenics. My flesh is programmed to want food three times (or more per day); I don't have to have food for about 30-40 days, but I've been habituated to it. By fasting, I am practicing to let my spirit/person/soul have sway over the desires of the flesh. It builds up the "spirit muscle" so that when other kinds of fleshly desires may rear their ugly heads, my spirit has had practice at saying 'no' to such things. I see it very much along the lines of junior high basketball players practicing dribbling around chairs and crossing-over their dribble. This develops in them a skill, or a natural predilection, that is immediately transferable to the game situation.
I have found in my own life that when I am fasting consistently, I seem to have more spiritual power. I am "in shape" in spiritual life. When I don't fast, I tend to get a bit flabby and lazy and out of shape.