A spiritual struggler must be free of any arrogance, and must follow the royal path of moderation, without turning away in either direction, neither loving comfort nor exhausting his body with excessive abstinence.
St. Basil the Great
Physical struggle unaccompanied by spiritual struggle is more harmful than disease. It is the cause of unusual intensification of spiritual passions.
Physical struggle, as yet not illuminated by spiritual discernment, always has within it much that is vain and excessive.
St. Ignatius Brianchaninov