2 Corinthians 4:17
For our light affliction, which is but for a moment, worketh for us a far more exceeding [and] eternal weight of glory;
Note 18 at 2Co 4:17: Paul's afflictions were not "light" because they were few in number or not very severe. He gave a partial list of some of the afflictions he endured for the Lord's sake in 2Co 11:23-30. There he listed beatings, stonings, imprisonments, and many other forms of persecution that were much greater than most Christians today have suffered. Paul's afflictions were "light" because of his attitude toward them.
The difficulties we face in our service to Christ are small, little, slight, and momentary, compared to our future lives of eternal glory with the Lord. Nothing--no affliction, no troubles, and no persecution that we face in this life--can compare to the more exceeding and eternal weight of glory reserved in heaven for us (1Pe 1:4).
If Paul had more afflictions than we do yet his afflictions were "light," then how can we justify complaining about our "heavy" burdens? It's not our external situations that are the problem; it's the lack of being renewed in our inner selves daily that is the problem.
Note 19 at 2Co 4:17: 2Co 4:17-18 gives a very practical reason Paul's afflictions were only "light" (see note 18 at this verse). It was because he evaluated every situation in the light of eternity. Any problem he encountered in his lifetime was only for a moment, compared to the eternity he would spend with the Lord. Just the time element of eternity shrinks the problems of this life into relative insignificance.
As bad as anyone's marital situation may be, it will only last for this lifetime (Mt 22:30 and Mr 12:25). If we thought on the blessings promised us that will last throughout all eternity, we could rejoice through the worst of marriages. The worst any disease could do is kill us. That's not the end of existence. We will live forever with the Lord. Thinking on this will take the sting out of death (1Co 15:55).
Any situation we face can be reduced to a manageable size if we will put it into the perspective of eternity (see note 5 at Joh 14:2).