Some commentators describe Ecclesiastes 3:12 as negative because they understand the phrase, “there is nothing better,” as implying something “second-best.” They almost seem insulted that God has “tossed them a crumb.” But look again at what God has counseled that we should do! In verse 12, He advises us to rejoice and do good in our lives, and in verse 13, to eat, drink, and enjoy the good of our labor because these things—the food, the drink, and the ability to labor—are gifts of God.
If we reword these verses into the first-person voice, it reads, “There is nothing better than that I should be joyful and do good as long as I live, and to eat and drink and take pleasure in all my work—this is God's gift to me.” How much good can be accomplished in a life lived with the attitude that He counsels us to live with? What does God more specifically mean by “do good”? What He means should be taken in a moral and ethical sense. To do good is to do good works, and that is our assignment all the time! God is most certainly not tossing us a crumb.
Ephesians 2:10 tells us that doing good is the very reason for our calling! “For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them.” Regardless of a trial God may have specifically assigned us, doing good works is always our assignment, whether within that specific trial or free from whatever particular discipline the trial might normally impose.
Thus, in Ecclesiastes 3:10-14, God is telling us to take joy in His employment of us before the world in doing good at home for those we live with, doing good work on the job, doing good in serving the brethren, and doing good within our community as we have occasion, using our spiritual gifts to the best of our abilities.