Not long ago, Dr. Alice Domar, director of the Mind/Body Center for Women's Health at the Beth Israel Deaconess Medical Center in Boston, saw four female patients in a row. All four were struggling—one in her 20s with PMS, another in her 30s with infertility, a third in her 50s with menopause, the last in her 70s with breast cancer. To each, Domar found herself saying basically the same thing: "You need to put yourself on your own list of priorities."

Domar, 43, a health psychologist who is married and has two daughters, believes that emotionally induced tension exacerbates a legion of illnesses—including cardiovascular disease, chronic fatigue and cancer—that trouble today's overworked, under-rested women. "These are organic diseases," says Domar. "But they cause stress. And it is the stress that interferes with the treatment and recovery." A five-year study by Domar published last year found that infertile women who took stress-relief classes at the Mind/Body Center were almost three times as likely to give birth as those who underwent only the medical fertility treatments. And as Domar argues in her bestselling book Self-Nurture—and in the following interview with correspondent Nancy Day—good health requires more than physical fitness: "You have to be willing to nurture yourself."

Why is stress so important?

An intriguing body of evidence suggests that expressing emotion in appropriate, balanced ways can strengthen our hearts, our immune systems and our overall resistance to disease. The Mind/Body Center has found evidence that everything from blood pressure to menopausal symptoms improves in patients who practice stress-reduction techniques. There is even increasing evidence that depression hampers fertility and that relieving depression in infertile women increases pregnancy rates.

Are modern women more stressed than their mothers were?

Yes. Women are more isolated now, often with their families further away. So many women need to work, along with raising their children and tending to their husbands, families and friends. When women try to do everything, we end up at the bottom of our own list, giving time to everyone but ourselves.

How do you teach self-nurture?

First we give our patients a relaxation tape and advise them to spend at least 20 minutes a day with it. Then I ask them to create a time pie, identifying chunks of time they spend in unrewarding or self-sacrificing activities. I redirect them toward soul-nourishing activities, ones that yield feelings of serenity and joy. We also teach "mini-relaxations," a breath-focus meditation that helps them shift from tense, shallow chest breathing to deep, relaxed abdominal breathing. The minis are the perfect portable stress managers. And we do "cognitive restructuring."

What's that?

We help women examine their negative thoughts. I get a lot of breast cancer patients who think the reason they are sick is because they did something wrong. I get infertility patients who feel they are being punished for having had abortions when they were teenagers. Cognitive restructuring, helps them deal with reality—not through denial but by repeating, for example, "I am not my job," "I embrace the challenge," "I am not a victim." Many women are uncomfortable with anger. Little boys are encouraged to get it out, but little girls are told to be nice. When they grow up, they keep their anger inside. It tends to eat them up.

In what other ways can women relieve stress and be healthier?

If we could get Americans to walk every day, we probably wouldn't need half the hospital beds in this country. I tell my patients: If I could give you a pill to treat anxiety and depression, reduce the risk of breast and colon cancer, improve cardiovascular health, had no side effects and didn't cost anything, wouldn't that be a good deal ? Walking does all that. If I could get women to do just three things to better care for themselves I'd say, Do the minis every time you're stressed, walk every day, and write in a journal—write about yourself.