"See what cause the saints have to be frequent in the work of thanksgiving. In this Christians are defective; though they are much in supplication, yet little in gratulation. The apostle says. "In everything give thanks" (1 Thess. 5.18). Why so? Because God makes everything work for our good. We thank the physician, though he gives us a bitter medicine which makes us sick, because it is to make us well; we thank any man who does us a good turn; and shall we not be thankful to God, who makes everything work for good to us? God loves a thankful Christian. Job thanked God when he took all away: "The Lord hath taken away. Blessed be the name of the Lord" (Job 1.21). Many will thank God when He gives; Job thanks Him when He takes away, because he knew that God would work good out of it. We read of saints with harps in their hands (Rev. 14.2), an emblem of praise. We meet many Christians who have tears in their eyes, and complaints in their mouths; but there are few with their harps in their hands, who praise God in affliction. To be thankful in affliction is a work peculiar to a saint. Every bird can sing in spring, but some birds will sing in the dead of winter. Everyone, almost, can be thankful in prosperity, but a true saint can be thankful in adversity. A good Christian will bless God, not only at sun-rise, but at sun-set. Well may we, in the worst that befalls us, have a psalm of thankfulness, because all things work for good. Oh, be much in blessing of God: we will thank Him that doth befriend us."
Taken from Banner of Truth's Puritan Paperback, "All Things for Good," by Thomas Watson, pp 62-63.