The thing is, I started a novel over the Christmas break. I wrote 12 and 14 hours a day, slipping it in between Santa Claus duty and cooking for our annual New Year’s hoppinjohn party. When I went back to the office after the holidays, I began working on the book in the early  mornings before work and on weekends. Which is exactly when I used to work on my blog.

Whenever you take on another work commitment, you might want to think about what you’re NOT going to do to make time for the new priority. That’s easier said than done. Usually those new commitments sneak up on you as a new client assignment, a special request from your boss, or an irresistible opportunity for advancement, recognition or visibility. They’re generally not the kinds of things you want to turn down. In an ideal world, you’ve got the capacity to take on more.

But if your plate is already full, you can’t keep piling on more and more without dropping something. Most of us have figured out by now that we can more consistently perform at higher levels when we avoid letting ourselves get completely exhausted. Also that reaching absolute exhaustion requires an inconvenient recovery time when we’re just not our sharpest.

Like they say, we all get the same number of hours in the day. Einstein didn’t get more than 24 of them, and neither does President Obama. Come to think of it, you can fit a lot into 24 hours. Most days, I feel like I have a fairly balanced life. But it stays that way only if I say no to some things, or at least put them on hold for a time while something else takes that priority spot.

Have you had to make choices in what work you can take on when? I’d love to hear what other people have experienced with work-work balance. Or if you tend to just take that extra work time out of your personal life hours.

Tribe’s recent research with New Generation employees indicates that the younger employees may expect flexibility even more than their Boomer colleagues. Although a story on NPR this morning pointed out that the employees who need flexibility most are the low-wage workers, a disproportionate number of which are single moms.

A family-care focus is a common theme among the companies listed on Fortune’s latest list of Best Companies To Work For. “They don’t just take care of the employee, they take care of their whole families,” said my colleague Jennifer Bull in her Good Company Blog.

One of the things families need most is flexibility. Jennifer Ludden, the NPR correspondent responsible for the piece I heard this morning, describes one example of family-friendly flexibility on the part of Family Fare grocery near Grand Rapids, Michigan. Tina Burgess, mother of two boys, had been a part-time employee at the grocery for years when she was offered a full-time position.

“Burgess wanted the benefits that came with that job, but there was a problem: it started at 5 a.m. Her husband left for work at 5:30, so Burgess needed to be home to get her children to school. Her manager worked it out.”

Burgess goes into work at 5, but calls her teenage sons at 7 to wake them up. (The boys sleep with their cell phones on their pillows.) She then takes her 30-minute lunch break at 7:15 in the morning, to drive home, pack lunches, and get her kids out the door to school. Although the boys are old enough that they might be able to handle the morning routine on their own, Burgess feels strongly about being there.

“’Sometimes in the morning, I get a feel for if it’s going to be a bad day,’ she says. ‘Maybe they want to say something before they go to school. If I wasn’t there, they wouldn’t be able to.’”

What’s more, offering flexibility could make your employees healthier and contribute to the bottom line of the company’s profitability. Ludden cites a recent NIH study on the correlation between job flexibility and employee health, indicating that those employees with more flexible management had both better physical health reports and higher job satisfaction.

The best news for employers? Flexibility is cheap. Even with hourly workers, there are ways to accommodate employees’ family responsibilities, from allowing workers to trade shifts to giving them five minutes to call home to make sure the kids got home from school okay. As we come out of the recession, and the competition for workers heats up again, you can bet flexibility will remain one of the best ways to both recruit and retain talent.