There are, then, four types of spiritual poverty, and each gives birth to a corresponding kind of grief, as well as to a corresponding form of spiritual solace. In the first place, freely-embraced physical poverty and humility–and that means hunger, thirst, vigils and in general hardship and tribulation of body, as well as a reasonable restraint of the senses–begets not only grief, but also tears. For just as insensibility, callousness and hardness of heart develop as the result of ease, soft living and self-indulgence, so from a way of life marked by self-control and renunciation come contrition of heart and compunction, expelling all bitterness and generating a gentle gladness.
It is said that without contrition of heart it is impossible to be free from vice; and the heart is rendered contrite by a triple form of self-control, in sleep, food and bodily ease. When through such contrition the soul is freed from vice and bitterness, it will certainly receive spiritual delight in their place. This is the solace on account of which the Lord calls those who grieve blessed.
~St Gregory Palamas (Philokalia vol.4, p.313)