Some indeed preach Christ from envy and strife and some also from good will: the former preach Christ from selfish ambition, not sincerely, supposing to add affliction to my chains, but the latter out of love, knowing that I am appointed for the defense of the gospel. What then? Only that in every way whether in pretense or in truth, Christ is preached, and in this I will rejoice, yes and will rejoice. Philippians 1:16-18
The book of Philippians was written from a prison cell, and yet it is referred to as the epistle of Joy. It would have been very easy for the Apostle Paul to complain, but he didn't. He highlighted one of the struggles he had to deal with. There were some preachers who were thankful Paul was in prison so that they could further their ministries. Paul said their motivation was selfish rather than sincere.
If a person gets into ministry because they have something to prove, or out of spite, or perhaps they see it as a competition; it can be dangerous to themselves and to the ones they minister to. Ministry in the flesh is dangerous and we want to avoid it all costs. Let the Lord deal with that situation, He is far more capable than you and me. Although this was certainly a concern to Paul, what could he do from where he was? He could not control the situation. He writes, "WHAT THEN?", or in other words, what am I going to do? Then Paul tells us what he decided to do, he decided to rejoice. In fact, he made a choice to rejoice. Whether the motives were pure or impure on the part of those preaching was now beside the point, Paul found reason to rejoice and so can you.
Rejoice in who Jesus is and what He has done. Don't allow yourself to get wrapped up in what that person said about you, or what their trying to do. Keep your eyes on Jesus and keep running the race rejoicing all the way.