Who sent you?
Acts. 7:35
“This is the same Moses whom they had rejected with the words, ‘Who made you ruler and judge?’ He was sent to be their ruler and deliverer by God himself, through the angel who appeared to him in the bush.”
When you know you have been sent by God Himself then:
a) you can return to the place of your failure.
b) you can face those who previously rejected you.
c) you can give people more than they ever would expect. (He was accused for trying to be a judge but he became their deliverer.)
Some missionaries get detached from their sending church. Some look back to when they were commissioned and sent out by wonderful prayers and encouragement, but today it is a distant past.
However what keeps them doing what they are doing is knowing it was God Himself who sent them.
Whether you are crossing borders or crossing the street to tell people of the love of God knowing who sent you can be crucial to keep going.
Missions Paul 