Let me ask you a question. What, if anything, are you signed on and sold out to with your whole life? What is it in your life that must happen? That must be pursued, fought for, invested in, and contributed towards? What is it, if there is indeed anything, that has won your heart, soul, mind, and strength so much that you go to bed and wake up thinking about it, and your days are consumed with it?
For most people - most Christians included - there is not an answer to that question. Or if there is, it is something that is questionable concerning its worthiness of such passion, commitment, and steadfastness of spirit.
There is but one thing in scripture that is elevated as worthy of such non-stop loyalty, and it is found in 1 Corinthians 15:58, from the pen of Paul: "My dear brothers, stand firm. Let nothing move you. Always give yourselves fully to the work of the Lord, because you know that your labor in the Lord is not in vain."
The very vocabulary that the Bible employs here summons that rarely touched "something" found deep inside the human soul reserved for only what is determined by each of us to be the worthiest of things. It is the uncompromising language of purity of devotion, seldom used by human beings for anything, yet unapologetically employed here for but one thing.
The work of the Lord.
The Bible believer is called to do the work of the Lord. To be about it always. To give themselves fully. To allow nothing to stop them.
Why? Because it is the labor that is not in vain; that makes a difference; and that lasts.