"The everlasting God...neither faints nor is weary."
Are you spiritually exhausted? You may need to look at the source where you are spiritually fed. The only source should come from God because we are to do the work for him. Otherwise, you'll be exhausted on your own.
The job is exhausting as a disciple and a servant of God until the souls we teach learn to feed on God. An old friend told me, "Before other souls learn to draw on the life of the Lord Jesus directly, they have to draw on it through you; you have to be literally "sucked" until they learn to take their nourishment from God."
Don't ever tell God that you're tired and exhausted. He saved and sanctified you to exhaust you. Be exhausted for God, but remember that your supply comes from Him. "All my fresh springs shall be in Thee."