Still in prison, Paul is still able to glorify God. Despite his current state, what Paul has been doing is continuing to advance the Gospel (v. 12). At the moment, I believe it is safe to say that most of us reading this are in a better position than Paul. Regardless of our status, we should always be pursuing the progression of the Gospel. Paul took the extra step to even tell his guards that what he is doing is all for Christ (v. 13). Even those who are in prison with him are now proclaiming the name of Christ without fear (v. 14).
In this era, preaching the Gospel is one of the toughest things to do, especially in a upper-middle class community. It's encouraging to see that people are continually preaching the Gospel to fellow friends and neighbors, but sometimes, there are times where the Gospel message is not preached out of love (v. 15-17). Despite whatever motives are being used, we should still be appreciative of the Gospel message that is being shared. If God does accomplish good using the means of the wicked, continue to rejoice. One group of people who come to mind is those who hold up those picket signs on college campuses condemning people to hell and what not. As "obnoxious" as they sound, some people do come to know Christ because of the type and style of the Gospel that is being preached. Regardless of the tone and attitude of these people, Paul would still rejoice; however, Paul would most likely not have ordained those who cannot share the Gospel out of love as ministers. Paul knew that the Gospel message would not be preached with love 100% of the time, but regardless of the reason for preaching the Gospel, rejoice in the advancement of the Gospel.
I also wonder how much of our own intentions are also mixed when we preach the gospel. Even if we think we are doing it out of love, there may be other motives as well. So it's good to also be able to search our own hearts too. Despite this, it's good to know that God does what He wants and saves people and uses us, as imperfect people, to bring the gospel to others. It is humbling.