Of course, the catechism answer is "The chief end of man is to glorify God and to enjoy Him forever." But do we even know what that means? Do we know what it looks like? Do we actually know what to do, every day, in order to fulfill our high calling, or do we just say these words and let them, like so many theological terms we know we subscribe to somehow, just float around like so many flies buzzing loopily around the house - impossible to catch or even get a good snapshot of because they are never grounded?
1 Thessalonians 5:18 tells us, "In everything give thanks: for this is the will of God in Christ Jesus concerning you."
So simple. And so vast.
Gratitude is what God wants from us. Not sacrifice. Not long prayers. Not putting large offerings in the tithe box, giving our lives to 'full-time Christian work,' or even keeping his commandments. He wants our thanks. Is it any coincidence that in Romans 1, when God gives men over to their lusts, that it is precisely because they did not acknowledge God as God, or give Him thanks?
Giving thanks means that we are humble and that we recognize our beneficiary. We realize we are not enough in and of ourselves, but that someone is giving of themselves to bless us. We realize our smallness, and God's greatness. This is what He wants from us. He wants us to see that the good in our lives is not of ourselves, and to note that it is Him from whom we have all things. And this is how we glorify God and enjoy Him.
This is the will of God for us. And it's why I write lists of things that I am particularly (on a given day) glad to have received from His hand. The world, and all the broken and beautiful and living and dying things in it, are gift.
Do what God asks of you, the thing He wants you to do the most: praise Him.