Paul longed for the salvation of his people, the Jews. Their conversion to Christ was the desire of his heart. It was what he really wanted in life.
What do you want?
Paul was not content that his people were religious. He knew that religion does not save. He saw their fruitless efforts at establishing their own righteousness as just exercises in religion... outward efforts. He knew their feelings for previous to his conversion he had shared their beliefs. Now he desired salvation for those of his race. He longed for the end to their rejection of Christ.
How do you feel about those close to you? Are you satisfied if they have good jobs, pay their bills, treat their families well, dress handsomely, prosper and enjoy good health? Or do you really care about them? Do you care about their souls? Do you desire salvation for them above all else?
Paul's deep desire drove him on day after day in his missionary work. He endured hardships contentedly because he knew that all things here are temporary and that eternal things deserve priority. When he came to the end of life he knew he had done all he could do. Let him tell it: "For I am now ready to be offered, and the time of my departure is at hand. I have fought a good fight, I have finished my course, I have kept the faith: Henceforth there is laid up for me a crown of righteousness, which the Lord, the righteous judge, shall give me at that day..." (II Timothy 4:6-8).
Are you doing everything possible to reach people for the Saviour?
Is the salvation of the lost the desire of your heart?