The purpose of asceticism is to accept asceticism. Once this has happened, it is no longer useful. Mere austerity is quite sufficient, and that only to avoid an overabundance of things you might miss.
Buddhism is first and foremost a psychological process. Whatever we call “spirituality” is simply a continuation of the developed ability to see in this world. The world simply expands; rather, your awareness of the size of this “world” expands.
I think of the monks sitting in their caves for 3 years. Do you not think powerful feelings of fear and fatigue and loneliness plague them? Do they not fear going mad? We tend, I think, to think of them as other than us, but this is not true. They merely go farther than most of us are willing to go, but they suffer for it. Of this I have no doubt. But that suffering has another side; it ends; it can be traversed.
But becoming comfortable with suffering: this is the asceticism of the soul, of the emotions. If you can handle a lot of pain, you can process trauma as it happens, and leave it behind when it is done. The value of this knowledge for your capacity for tranquility cannot be overstated. Most of us know there are things that could happen that would deeply disturb us. If we have already learned the skill of being disturbed, letting it flow through us–ripping us to shreds before we reconstitute–then we need fear nothing.
And fearlessness is life.