"If you are willing to suffer, very well, then the treasure and consolation which is promised and given to you is so great that you ought to suffer willingly and joyfully because Christ and his suffering is being bestowed upon you and made your own. And if you can believe this, then in time of great fear and trouble you will be able to say: Even though I suffer long, very well then, what is that compared with that great treasure which my God has given to me, that I shall live eternally with him? ...
When one knows this it is the more easy and bearable, and one can comfort oneself by saying: Very well, if I want to be a Christian, I must also wear the colors of the court; the dear Christ issues no others in his court; suffering there must be...
So in our suffering we should so act that we give our greatest attention to the promise, in order that our cross and affliction may be turned to good, to something which we could never have asked or thought. And this is precisely the thing which makes a difference between the Christian’s suffering and afflictions and those of all other men. For other people also have their afflictions, cross, and misfortune, just as they also have their times when they can sit in the rose garden and employ their good fortune and their goods as they please. But when they run into affliction and suffering, they have nothing to comfort them, for they do not have the mighty promises and the confidence in God which Christians have. Therefore they cannot comfort themselves with the assurance that God will help them to bear the affliction, much less can they count on it that he will turn their affliction and suffering to good...
Since we know then that it is God’s good pleasure that we should suffer, and that God’s glory is manifested in our suffering, better than in any other way, and since we are the kind of people who cannot hold on to the Word and our faith without suffering, and moreover since we have the noble, previous promise that the cross which God sends to us is not a bad thing, but rather an utterly precious and noble holy thing, why should we not be bold to suffer? As for those who will not suffer, let them go and be cavaliers; we preach this only to the devout who want to be Christians, the others wouldn’t carry it out anyhow. After all, we have so many assurances and promises that he will not allow us to stick in our suffering but will help us out of it, even though all men should doubt it. Therefore, even though it hurts, so be it, you have to go through some suffering anyhow; things cannot always go smoothly. It is just as well, nay, a thousand times better, to have suffered for the sake of Christ, who promised us comfort and help in suffering, than to suffer and despair and perish without comfort and help for the sake of the devil.
This, you see, is the way we teach concerning suffering..."
Luther, M. (1999). Luther’s Works, vol. 51: Sermons I. (J. J. Pelikan, H. C. Oswald, & H. T. Lehmann, Eds.) (Vol. 51, p. 199, 201, 208). Philadelphia: Fortress Press.