And, behold, there came a voice unto him, and said, What doest thou here, Elijah? And he said, I have been very jealous for the LORD God of hosts: because the children of Israel have forsaken Thy covenant, thrown down Thine altars, and slain Thy prophets with the sword; and I, even I only, am left… ~ 1 Kings 19:13-14 

Elijah was a man of like passions with ourselves. We all know that when we have passed through any great excitement of high joy there almost always comes following, a corresponding reaction and depression.

But thus saith the Lord unto thee, “It may be thou hast not laboured in vain as thou hast supposed.” Elijah knew nothing of the seven thousand men that God had in reserve. You don’t know what converts God has given you. There are scattered up and down the world, perhaps, some precious ones who owe their salvation instrumentally to you, and could they all stand before you, you would blush with shame at the thought of leaving a harvest-field that has really been so prolific, though not in your sight. Go back again to thy work, for the Lord has blessed thee. Play not the fool by deserting the post where He will give thee honour yet. Oh! thou true servant of God, the Lord will not suffer thee to be rejected. If they have rejected thee, they have rejected thy God also. If thou hast been faithful to His truth, leave thou that matter to Him-go thou back to thy work.  ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/3498.cfm