Labor Day seems like a fine day to consider what work means to life and vice-versa; and especially for me since I've just started an immersive web-programming/development course.
You might think that this is a radical change for me, going from English major to programming, but I've always been interested in science and especially computers. I mean, I had all the classic kid-scientist toys: microscope, chemistry set, physics set, telescope, scissors for cutting through electrical cords when the fan was still on, etc.
I also took just about all the computer science classes that Bard offered when I was there. I started by learning to sort using wooden blocks (cedar, according to the teacher, so after learning to sort we could keep the moths off our sweaters); and I ended by learning assembly code. I wasn't one of the kids programming his TI-85 to play Monopoly in high school, but I did build some websites from scratch in college. So let's not say that this is a big change in interests, just a change in focus.
Now, after that big introduction, I have to be honest: I don't really have all that many thoughts on changing focus. Or rather, I have one big thought: if you're changing focus or even having a more radical career shift, it probably means more to you than it does to anyone else in the room. I don't mean "it's all in your head, man"; I mean, everyone starts somewhere. So even if you started by sorting cedar blocks (which I still have in my closet, keeping my sweaters moth-free), there's still no telling where you'll end up.
But just to prove that I haven't given up all my literary interests, I'll add that many of my favorite writers basically began writing in the middle of some other career, like Sherwood Anderson. Anderson operated a successful business selling paint when, at the age of 36, he suffered a pretty serious nervous breakdown, including disappearing for four days and walking (probably) from Elyria, OH, to Cleveland, OH. (Which really shouldn't take four days.) Only then did he begin writing.
So, if you're changing careers, just remember: as long as you don't disappear for four days, you're doing OK. Heck, even if you do disappear for four days, you might be doing great. Just look at Sherwood Anderson.