A view on work that's been floating around the culture of American Christianity, if not really articulated often, lately goes something like this. Your job is a fantastic gift from God. This is because He has provided you with a network of relationships and put you in a sphere of influence to provide you with many fruitful opportunities for sharing His gospel of life. Invest in these relationships and keep working with your coworkers so that they might know the truth through your authentic witness and be saved.
A related outlook on work that has been influencing me lately goes like this: I am truly thankful that God has gifted me with a skill that commands quite a premium salary in today's world--computer programming--and the opportunity to put it to use in a satisfying job. I can't wait to start pulling in a paycheck so that, by careful budgeting and financial planning, I can give as much of it as possible away to my church, my friends in ministry, and other worthy causes.
I tried to make both of these ideas sound as good as possible, but they are related in how they are both mistaken: they both make the earthly practice of work a means to a spiritual end--evangelism or the gift of generosity. Underlying this is a division of different vocations into "spiritual" and "secular" camps and the conception that one is more important or significant than the other. In reality, Jesus has sent us into "all the world" (Mark 16:15) and, with a few exceptions (hit man, drug runner, professional con artist...) we can't really say there are places a Christian "shouldn't" work.
Don't get me wrong--it's great that work gives us chances to share the gospel or support great ministries. But there is more to it than that. God "worked" to create the heavens and the earth (Genesis 2:2). Jesus worked as a carpenter for most of His earthly life. (Mark 6:3) Even before the Fall when everything was perfect, Adam had work to do in the garden of Eden. (Genesis 2:15) The curse means that our work will be filled with toil, frustration, difficulty, pain, and conflict (Genesis 3:17-19), but the original God-given purpose of our work--participating in God's creative work--has not changed. In our work we mimic not only God's creativity, but also His character. I believe that legitimate work is intrinsically glorifying to God, whatever else comes of it. This also implies that we should pursue excellence in whatever work we do--do you think Jesus did shoddy work as a carpenter? Do you think God cut some corners when He was making the world? (Well, there is the existence of cats, but that's another issue)
A few things to note: by "work" I don't just mean a job you get paid for. I am continuing to do research with the same project I did my honors thesis on; I don't get anything from it except my name on a paper, but I still consider it work. Stay-at-home moms work harder than many 9-to-5 wage earners. Second, it's probably not a good idea to wait for God to reveal to you exactly what He wants you to do with your life, closing every other door. God's calls to people in the Bible to specific jobs or ministries are relatively rare (but usually extraordinary, which is why they're so well-documented in its pages); in general, the command is "whatever you do, do it to the glory of God." (1 Cor. 10:31) And finally, I wanted to mention that work's being exhausting isn't always because of the fall. I know this from the inimitable feeling of peace and satisfaction you get from kicking back and resting after a hard day's work well done. This feeling is, I think, completely Biblical.
So whatever you do with yourself, whether it be in, with, or outside the church, know that your work is meaningful in the coming Kingdom apart from whether it wins anyone to Christ or pays for a well in Africa. (Though these things might motivate us to excellence in what we do) As a software programmer, I attempt to imitate God's creativity, order, and love for building complicated things in my work. An artist might convey or cultivate an appreciation for the beauty of creation. And so on. It's not my place to prescribe how others should go about their work; it's up to all Christians to discover how to glorify God wherever He puts them.