It would be nice to think that God's servants always feel confident that working for the Lord is worthwhile. But they are all human and may doubt or be discouraged when problems overwhelm them. When that happens, they need to ask the right questions and look to the right people for the answers - as John the Baptist did. He believed that he had been called by God to announce the Messiah and call people to repentance. When Jesus came to be baptised John proclaimed Him as the Lamb of God who takes away the sins of the world (John 1:29).
 
John continued to be a vigorous evangelist, and he had conversations with King Herod Antipas. John called him to repentance too, because Herod had fallen in love with his brother's wife, divorcing his own wife to marry her. This was against God's law (Leviticus 18:16). But instead of repenting, Herod was very angry; he had John arrested and imprisoned. Herod was too afraid of the crowd to kill him at that time, because John was so popular (Matthew 14:3-5). But the prison was a dreadful place and John longed for reassurance that he has not got it all wrong, and wasted his life. So he sent his question to Jesus.
 
The answer was both an encouragement and a warning. Jesus spoke of Himself in the words of Isaiah (Isaiah 29:18-21; 35:5-6; 61:1). His deeds validated His identity. John had not been mistaken, but had been privileged to proclaim Him to the world. Prison (and John's subsequent execution) was not his punishment for getting it wrong, but a way of identifying with his suffering Saviour. It was not a time to doubt but be confident; not a time to regret his ministry but to give thanks to God for the privilege of ministering in the Name of Jesus. Blessing would come to John as he stood firm, despite the suffering.
 
Our human hearts are less stable than we think. When everything is going well we feel strong, but when problems cloud our horizon and suffering is close to home, we are inclined to be discouraged and doubt. If we ask our own hearts we will get an answer according to how we are feeling; if we ask our friends we may get sympathy and comfort, but it is never enough. We need to go to Jesus, repenting of our sin but holding firm to what is true. It is His opinion which really matters. Blessing does not come from changing our circumstances but in holding firmly to the Lord Jesus Christ as our Saviour, Sustainer and Friend. Do not let the world, flesh or devil drag you away from trusting in Jesus: His identity is validated by His words and deeds so be encouraged - your work for Him is not in vain (1 Corinthians 15:58).