The Lord said: ‘He who endures patiently to the end will be saved’ (Matthew 10:22). Patient endurance is the consolidation of all the virtues, because without it not one of them can subsist. For whoever turns back is not ‘fit for the kingdom of heaven’ (Luke 9:62)….Patient endurance kills the despair that kills the soul; it teaches the soul to take comfort and not to grow listless in the face of its many battles and afflictions….
He, then, who knows what is to his benefit should struggle to acquire this virtue before anything else, according to St Basil the Great. St Basil advises us not to fight against all the passions at once, since if we are unsuccessful we might turn back and no longer be fit for the kingdom of heaven. Rather we should fight the passions one at a time, and start by patiently enduring whatever befalls us. This is right; for the person who lacks patient endurance will never be able to stand fast.
…in spiritual warfare it is impossible to find a place anywhere in creation in which a battle is not being waged. In the desert there are wild beasts and demons and other malefic and terrifying things; in places of solitude and stillness there are demons, trials and temptations; in the midst of human company there are demons and men who try one and tempt one. There is no place anywhere where one is unmolested; and, because of this, without patient endurance it is impossible to find peace.
~St Peter of Damaskos