There is a vanity that takes place on earth, that there are righteous people to whom it happens according to the deeds of the wicked, and there are wicked people to whom it happens according to the deeds of the righteous.

I said that this also is vanity. And I commend joy, for man has nothing better under the sun but to eat and drink and be joyful, for this will go with him in his toil through the days of his life that God has given him under the sun.

Paul reminds Timothy that it is God, who richly provides us with everything to enjoy. But don't expect to find happiness in this world - enjoyment of eating of drinking will not bring everlasting happiness - the song writer concludes in little further on; "however much man may toil in seeking, he will not find it out." It is only in the grace of God can we have peace; our soul is satisfied only in Christ Jesus. For the kingdom of God is not a matter of eating and drinking but of righteousness and peace and joy in the Holy Spirit (Romans 14:17). So the verse is ellipitcal - we are to be joyful in our circumstances; but the joy stems from knowing God, not our eating and drinking.