There are three indispensable requirements for a missionary: 1. Patience 2. Patience 3. Patience.
– Hudson Taylor
I would go on to say this should be indispensable for all Christians.
Isaiah 40:31:
But they that wait upon the LORD shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.