If Christ is Lord over all of life, then He must be Lord over work, too. Colossians 3 does not distinguish between the sacred and the secular, but between the life that Christ offers, (the "things above") and its alternative-spiritual death apart from Him (the "things on the earth"). This is clear from the preceding context (2:20) and the rest of chapter 3: "earthly" things include fornication, uncleanness, passion, etc. (3:5, 8); the "things above" include tender mercies, kindness, humility, etc. (3:12-15). Spirituality has to do with conduct and character, not just vocation.
It also has to do with the lordship of Christ. Christ is Lord over all of creation (1:15-18). Therefore, He is Lord over work. Whatever we do for work, we should do it "in the name of the Lord Jesus" (3:17), that is, with a concern for His approval and in a manner that honors Him. In fact, Paul specifically addresses two categories of workers-slaves (3:22-25) and masters (4:1)-in this manner.
The Spirit empowers us to live and work with Christlikeness. Spirituality has to do with character and conduct, regardless of where we work. Christ gives the Holy Spirit to help us live in a way that pleases Him (Gal. 5:16-25). That has enormous implications for how we do our jobs, our "workstyle" (see Titus 2:9-10).
Furthermore, Scripture calls us "temples" of the Holy Spirit (1 Cor. 6:19). An intriguing image: The Spirit enabled Hebrew workers to use their skills in stonecutting, carpentry, lapidary arts, and so on to construct a beautiful, functional house of worship (Ex. 31, 35). In an even greater way, we can expect the Spirit to enable us to use our God-given skills and abilities to bring glory to God.
God values our work even when the product has no eternal value. A common measure of the significance of a job is its perceived value from the eternal perspective. Will the work "last"? Will it "really count" for eternity? The assumption is that God values work for eternity, but not work for the here and now.
By this measure, the work of ministers and missionaries has eternal value because it deals with the spiritual, eternal needs of people. By contrast, the work of the shoe salesman, bank teller, or typist has only limited value, because it meets only earthly needs. Implication: that kind of work doesn't really "count" to God.
But this way of thinking overlooks several important truths:
(1) God Himself has created a world which is time-bound and temporary (2 Pet. 3:10-11). Yet He values His work, declaring it to be "very good," good by its very nature (Gen. 1:31; Ps. 119:68; Acts 14:17).
(2) God promises rewards to people in everyday jobs, based on their attitude and conduct (Eph. 6:7-9; Col. 3:23-4:1).
(3) God cares about the everyday needs of people as well as their spiritual needs. He cares whether people have food, clothing, shelter, and so forth.
(4) God cares about people, who will enter eternity. To the extent that a job serves the needs of people, He values it because He values people.