While in Ephesus Paul was a tent-maker working with his own hands to meet his own needs and the needs of those who labored with him and yet he still ministered daily. By some standards today Paul would be only a part time minister, yet to one who has read Paul's life over and over Paul's whole life, whether making tents or ministering at the School of the Tyrant, was full time ministry.
My qualifications by the way can be found in 1 Pet. 2:9 I am part of the priesthood of all believers who make up the Body of Christ. I do live in Japan and I have all the paperwork, diplomas, etc., etc. required for professional clergy, but I stashed it away and call myself a brother. No place in N.T. Scripture is anyone required to have papers or a Bible School Education and most of Paul's converts in the early Gentile churches were probably uneducated many of them slaves yet they comprised the elder-ship that emerged in those early churches, their qualification for ministry was their relationship with Christ and the life of the Spirit. Something that is missing in much of our so-called professional clergy today.