It must have been amazing to walk with Jesus. His disciples probably learned to find comfort in His presence. There are exceptions to this (Mark 4:38), but most of the time the 12 learned to lean on Jesus. As long as Jesus was there, things were going to be okay. There is a problem, Jesus would be going away. Jesus came to die for our sins and to ascend into Heaven. These men were empowered by the presence of Jesus, but that would soon be over. Jesus was not going to leave them alone. The promise of the Holy Spirit, a “comforter” would empower them. The Master Plan of Evangelism dives into this subject in chapter four. Here is a small snippet from the book…
The whole thing revolves around the person of the Master. Basically, his way was his life. And so it must be with his followers. We must have his life in us by the Spirit if we are to do his work and practice his teaching. Any evangelistic work without this is as lifeless as it is meaningless. Only as the Spirit of Christ in us exalts the Son are people drawn unto the Father.
Of course, we cannot give something away which we do not possess ourselves. The very ability to give away our life in Christ is the proof of its possession. Nor can we withhold that which we possess in the Spirit of Christ, and still keep it. The Spirit of God always insists on making Christ known. Here is the great paradox of life—we must die to ourselves to live in Christ, and in that renunciation of ourselves, we must give ourselves away in service and devotion to our Lord. This was Jesus’ method of evangelism, seen at first only by his few followers, but through them it was to become the power of God in overcoming the world.
But we cannot stop there. It is also necessary for one to see in us a clear demonstration of the way to live his life. Thus, we must understand another obvious aspect of Jesus’ strategy with his disciples.
Coleman, R. E. (2006). The master plan of evangelism (pp. 60–61). Grand Rapids, MI: Revell.