#IWSG: The Joy of the New vs. Progress

Until a couple of years ago, I was a beginner of a writer. I don't mean by this that I've become some kind of expert. Not at all. What I mean is that I used to write only beginnings.

What I have become is a finisher. I no longer write the first fifteen pages of something, then let myself get distracted by something shiny and abandon that project for a new one. 
And that's good! Because I'm finishing things, I'm able to submit them, and some of them are getting published and I might get to be a "real" writer full-time-all-the-time someday.
Neil Gaiman-I have this picture as my desktop background

But there are trade offs. Here lately, joy has been one of the trade-offs. 
If I want to "cash in" (metaphorically or literally) on what success I've already had, then I need to continue to produce work of that sort, even if my heart or brain or soul wherever the words come from wants something else right now. I can be very disciplined and I have been, for months now. That's good--I'll have work in a few anthologies in the next few months and a new book in April. You can't argue with results. 
There's a joy in a new idea, though. In working with new characters, new worlds, new premises, new settings. When I feel like I've been in revisions and editing too too long, I get bogged down. I worry about burning out. I need a little of that "open to anything" juice to get my blood pumping again. 
Snoopy understands joy.
So, that's what I'm trying to balance: progress on the current WIPs, with enough "play" time to keep my love and joy in the words. All this on the one or two hours I can steal for writing around the day job and family life. 
I especially love prompt writing for this. Prompts seem to be everywhere right now, as the NaNoWriMo machine starts chugging its engines. I've had invitations to work on several different kinds of flash fiction prompts here lately. 
I think I may have found the one that will work for me right now though--it's a ten minute prompt. You get a sentence starter, and you're only supposed to write on it for ten minutes. Then stop. Just dip your toes in. Start the new thing, but don't let it take over. 
I've only done a couple and I already love it. I'm getting that charge I get out of something new, but still leaving myself time and energy to make progress on the work that might get me paid. 
What works for you? How do you balance finishing things with keeping the joy?
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This posting is part of the Insecure Writers Support Group blog hop. To check out other posts by writers in a variety of places in their careers, check out the participant list. This group is one of the most open and supportive groups of people I have ever been associated with. If you write, you should check them out!