The book of Acts is the best aid in approaching our work. We do not find there anyone consecrating himself as a preacher nor anyone deciding to do the Lord's work by making himself a missionary or a pastor. What we do see is the Holy Spirit Himself appointing and sending men out to do the work.
Watchman Nee (2006). “Journeying Towards the Spiritual: A Digest of the Spiritual Man in 42 Lessons”, p.89, Christian Fellowship Publishers