Too often we over think this:
When our Lord called His disciples, He did it without irresistible pressure from the outside. The quiet, yet passionate, insistence of His “Follow Me” was spoken to men whose every sense was receptive (Matthew 4:19). If we will allow the Holy Spirit to bring us face to face with God, we too will hear what Isaiah heard— “the voice of the Lord.” In perfect freedom we too will say, “Here am I! Send me.”
– Oswald Chambers – Called by God
Mighty Anchor 