I have recently finished Don't Quit Your Day Job, edited by Sonny Brewer a collection of essays on writers' previous employment. I don't know if Sonny intended it quite this way, but the cumulative effect for a writer is very inspiring. It made me feel like the work I do is worth doing and the dues I pay are worth paying.
There's a temptation with any anthology to skip around, cherrypick the most promising-looking pieces first. I recommend with this book reading straight through. Brewer arranged these in such a way the book as a subtle arc. When you reach Steve Yarborough's concluding essay, you think, "Yes, right," and there's a fulfilling feeling of reaching a satisfying destination.
One of the consistent themes - and maybe when you're asked to write for a book like this, it's only natural that this emerges as a topic - is manual, even menial labor. Only John Grisham, a lawyer, writes about a white-collar job, and even he describes himself as the bottom rung of the ladder. Everyone else writes about construction jobs, pizza delivery, garbage collection. Surely a writer somewhere started out as a CFO or bank president, right? The point of many of these stories is that as much as we writers bitch about how hard we work, writing ain't nothing compared to real work. (Tom Franklin's essay about pizza delivery forcibly reminded me of my own days working for Domino's.)
A frequently recurring character in these essays is a co-worker doomed, unlike the author, to work as a builder, pizza-delivery person, or garbage collector for the rest of his life. Sometimes the coworker is likable, sometimes detestable, sometimes admirable, and sometimes pitiable. The bosses are almost all despicable: the worst one drugged and raped his female employees as one of the perks of being a bar owner.
Not every writer can point to some specific thing his day job taught him about writing. Often what the writer learns is I sure hate construction work, pizza delivery, or garbage collection. But it's clear reading vivid evocative descriptions that the sensory details of these day jobs imprinted themselves deeply. The strange thing is, we can't wait to lock ourselves in our towers and write. But then, so often, what we write about is the people we left back on the construction site.