an ascetic
Examples
I love my work with a frenetic and perverse love, as an ascetic loves the hair shirt which scratches his belly.
The beauty of a cuckoo is in its notes, that of a woman in her unalloyed devotion to her husband, that of an ugly person in his scholarship, and that of an ascetic in his forgiveness.
Then, as now, the philosopher seemed a living oxymoron: he was an ascetic sensualist, a spiritual materialist, a sociable hermit, a secular saint.
The student who deceives himself into thinking that he is giving his life like an ascetic in the spirit of sacrifice for art, is the victim of a deplorable species of egotism.
Tulsidas was a poor recluse who lived an ascetic life and prompted by an inner light, adapted an old epic in folk-verse which broke all barriers and spread far and wide.