When you have to fast, do not pretend illness. For those who do not fast often fall into real sicknesses. If you have begun to act well, do not turn back through constraint of the enemy, for through your endurance, the enemy is destroyed. Those who put out to sea at first sail with a favorable wind; then the sails spread, but later the winds become adverse. Then the ship is tossed by the waves and is no longer controlled by the rudder. But when in a little while there is a calm, and the tempest dies down, then the ship sails on again. So it is with us, when we are driven by the spirits who are against us; we hold to the cross as our sail and so we can set a safe course.
Excerpt taken from the book: The Sayings of the Desert Fathers