Martha Zeigler has high expectations for herself at work. So high that she routinely stays late at the office so she can toil uninterrupted by phones and coworkers.

Zeigler also has high expectations for herself at home. She wants to spend time with her husband, keep in close touch with her mother, serve her community.

But lately, the director of finance for the Metropolitan Sewerage District in Asheville, N.C., is finding it hard to meet all her expectations. "I am just torn," she says. "I can't focus well. I'm operating out of guilt rather than desire. At home, I think about work; at work, I think I'm neglecting my husband and I haven't called my mother in a week. It's a feeling of being under pressure all the time."

Sound familiar? The age-old struggle to be happy and successful at work and home, complicated by technology's ability to let you straddle both realms simultaneously, is making Zeigler and others like her feel utterly depleted. "How do I determine when enough is enough?" she asks. "What usually gets squeezed out is the replenishment time for myself—including sleep!"

Zeigler wants to attain work/life balance, but this popular goal is an elusive one, in part because "balance" isn't quite the right word. "It's not about 50/50 play/work," says Deborah Gilburg, a leadership development consultant in Holyoke, Mass. "It's really about figuring out how to be sustainable so you can keep your energy flowing, keep yourself healthy in the long term."

Here are some tips to help you become sustainable:

Ask yourself hard questions. Introspection takes guts. You need to determine how serious your problem is. Should you just wean yourself off evening e-mail, or should you consider a career change? Where are you going in life? What are your priorities? "Lots of creative thinking shows up when the priorities are clear," says Joyce Wooldridge, a life coach based in Suffolk, Va. "Employers can't be assumed to know what you want before you do. Neither can families."

The toughest question, says Tom Stern, humorist and author of CEO Dad: How to Avoid Getting Fired by Your Family, is: Has work become a retreat from problems at home, and if so, why? "There's a lot more criticism in the home on a daily basis; it's a lot more personal," he says. "In business people are pretty buttoned down, trying to avoid conflict. ...People at home whine, complain, tell you off."

To start finding answers, get a journal, says Gilburg, and spend a weekend thinking about what you want to do for yourself, your family and your community. "Ask yourself: What gives me the greatest energy, and what is sapping my energy the most?" she says.