From Lydia Brownback's new book, A Woman’s Wisdom: How the Book of Proverbs Speaks to Everything (Crossway, 2012), pages 170–171:
The way we use our time is always going to be shaped by how we view our time. Do we see it as a gift or as a right?
Those who view time as a gift can echo the psalmist who said, “Teach us to number our days, that we may get a heart of wisdom” (Ps. 90:12). They realize that their time is actually a God-given asset that they are to invest for God’s glory. They are cognizant of the fact that an hour gone by can never be relived.
Conversely, those who view time as a right tend to hoard their hours for selfish pleasure and often resent having to invest energy serving others — including God.
I wept with remorse some time ago when I realized what a guilty time-hoarder I can be. I’d been living through an exceptionally busy speaking season, and on top of this a book deadline loomed. Additionally, I had growing responsibilities at my place of full-time employment. I felt utterly overwhelmed. But rather than casting myself upon Christ and resting in the strength he so willingly supplies, I began to grumble. Grumbling led me to where it always leads — straight into a brick wall.
I was paralyzed by the volume of projects on my plate and found myself unable to make headway with any of it. I came home one day and cast myself onto my bed and cried out to God, “I just can’t do this anymore, Lord!”
Over the next day or so he answered my cry with the conviction that my trouble had more to do with my attitude than with my workload. It wasn’t his enabling that I’d really wanted. It was free time. In my desire to fill up more hours with relaxation and personal comforts, I had ceased to see that the work on my plate was a gift, as all kingdom work is. In writing and speaking, I’m not doing God any favors; he is blessing me with the privilege of getting to do it.

Personal comment: I firmly believe, though, that at the same time as we should view our work as a gift, as an opportunity, and as a challange to both serve God and to draw strength from God to be able to serve Him, rest and leisure time are God´s clearly declared will for us, as a part of our weekly life: Sabbath rest and Holy Days ...
- theremustbemore -