Read John 1:29-42
In this passage, John the Baptist took several actions.
First, he told those around him about Jesus. “Here is the Lamb of God, who takes away the sin of the world!” (v. 29). This was Jesus’s mission. Jesus did and taught a great many things, but He never lost sight of His mission of redemption through His death and resurrection. We cannot lose sight of Jesus’s primary mission either even while doing good things, for in doing so, we will lose the essential theme of the gospel.
Second, he encourage others to follow Jesus. John again pointed Jesus out as the Lamb of God and two of the men that we were with him followed Jesus (v. 35-37). John had a large ministry of encouraging repentance and baptism, but John knew his place. He proclaimed who Jesus was and encouraged his disciples to follow Jesus.
If someone asks who a disciple is and what do they do, point out John the Baptist as a good model.