By this he means that his life will bear fruit. This fruit consists of “labor”: when the apostle is able to work in the service of Christ in the spreading of the gospel, he does not consider that work a burden (not even in captivity). Instead he regards it as a fruit that he is allowed to bear for Christ. In his life he is like a fruit tree of Christ.1
22 If I am to live in the flesh, that means fruitful labor for me. Yet which I shall choose I cannot tell.