"... though the more abundantly I love you, the less I am loved" (2 Corinthians 12:15).
Natural human love expects something in return. But Paul is saying, "It doesn't really matter to me whether you love me or not. I am willing to be completely destitute anyway; willing to be poverty-stricken, not just for your sakes, but also that I may be able to get you to God." "For you know the grace of our Lord Jesus Christ, that though He was rich, yet for your sakes He became poor ..." (2 Corinthians 8:9). And Paul's idea of service was the same as our Lord's. He did not care how high the cost was to himself - he would gladly pay it. It was a joyful thing to Paul.
The institutional church's idea of a servant of God is not at all like Jesus Christ's idea. His idea is that we serve Him by being the servants of others. Jesus Christ actually "out-socialized" the socialists. He said that in His kingdom the greatest one would be the servant of all (Matt. 23:11). The real test of a saint is not one's willingness to preach the gospel, but one's willingness to do something like washing the disciples' feet - that is, being willing to do those things that seem unimportant in human estimation but count as everything to God. It was Paul's delight to spend his life for God's interests in other people, and he did not care what it cost. But before we serve, we stop to ponder our personal and financial concerns - "What if God wants me to go over there? And what about my salary? What is the climate like there? Who will take care of me? A person must consider all these things." All that is an indication that we have reservations about serving God. But the apostle Paul had no conditions or reservations. Paul focused his life on Jesus Christ's idea of a New Testament saint; that is, not one who merely proclaims the gospel, but one who becomes broken bread and poured-out wine in the hands of Jesus Christ for the sake of others.