1 Peter 5:2,NKJV, "... serving ... not by compulsion but willingly, not for dishonest gain but eagerly" I think, while talking to pastors, is good advice for all Christians, that is witnessing not because we have to or are supposed to but expressing love for our neighbors...

By the by, "in" has been preferred over the more accurate and pragmatic "into" or "within." It is useful to know when studying the Bible.