Nothing so makes the soul of those striving to advance on the spiritual path sluggish, apathetic and mindless as self-love, that pimp of the passions. For whenever it induces us to choose bodily ease rather than virtue-promoting hardship, or to regard it as positive good sense not willingly to burden ourselves with ascetic labor, especially with respect to the light exertions involved in practicing the commandments, then it causes the soul to relax its efforts to attain a state of stillness, and produces in it a strong, irresistible sense of indolence and slackness.
~St Gregory of Sinai
Prayerful Life 