1. Breathe Easily
“Breathing from your diaphragm oxygenates your blood, which helps you relax almost instantly,” says Robert Cooper, Ph.D., the San Francisco coauthor of The Power of 5 (Rodale Press, 1996), a book of five-second and five-minute health tips. Shallow chest breathing, by contrast, can cause your heart to beat faster and your muscles to tense up, exacerbating feelings of stress. To breathe deeply, begin by putting your hand on your abdomen just below the navel. Inhale slowly through your nose and watch your hand move out as your belly expands. Hold the breath for a few seconds, then exhale slowly. Repeat several times.
2. Visualize Calm
It sounds New Age-y, but at least one study, done at the Cleveland Clinic Foundation, has found that it’s highly effective in reducing stress. Dr. Cooper recommends imagining you’re in a hot shower and a wave of relaxation is washing your stress down the drain. Gerald Epstein, M.D., the New York City author of Healing Visualizations (Bantam Doubleday Dell Press, 1989), suggests the following routine: Close your eyes, take three long, slow breaths, and spend a few seconds picturing a relaxing scene, such as walking in a meadow, kneeling by a brook, or lying on the beach. Focus on the details—the sights, the sounds, the smells.
3. Say Cheese
Smiling is a two-way mechanism. We do it when we’re relaxed and happy, but doing it can also make us feel relaxed and happy. “Smiling transmits nerve impulses from the facial muscles to the limbic system, a key emotional center in the brain, tilting the neurochemical balance toward calm,” Dr. Cooper explains. Go ahead and grin. Don’t you feel better already?
4. Stop Gritting Your Teeth
Stress tends to settle in certain parts of our bodies, the jaw being one of them. When things get hectic, try this tip from Dr. Cooper: Place your index fingertips on your jaw joints, just in front of your ears; clench your teeth and inhale deeply. Hold the breath for a moment, and as you exhale say, “Ah-h-h-h,” then unclench your teeth. Repeat a few times. 
[Warning: I tried this once. My jaw is where my stress goes, and my (former) dentist told me I was grinding my teeth. So I made a conscious effort to relax my jaw. And since my stress had nowhere to go, I found myself getting angry at people, and being short with them. So I gave that up. I may shorten my life by a year or two, but I'll have a lot more friends by my bedside when I go.]
5. Compose a Mantra
Devise an affirmation — a short, clear, positive statement that focuses on your coping abilities. “Affirmations are a good way to silence the self-critical voice we all carry with us that only adds to our stress,” Dr. Elkin says. The next time you feel as if your life is one disaster after another, repeat 10 times, “I feel calm. I can handle this.”
[Try this, from Kurt Vonnegut, Jr.'s Timequake: "You were sick, but now you are well again. And there's work to be done."]
6. Be a Fighter
“At the first sign of stress, you often hear people complain, ‘What did I do to deserve this?’” says Dr. Cooper. The trouble is, feeling like a victim only increases feelings of stress and helplessness. Instead, focus on being proactive. If your flight gets canceled, don’t wallow in self-pity. Find another one. If your office is too hot or too cold, don’t suffer in silence. Call the building manager and ask what can be done to make things more comfortable.
7. Put It on Paper
Writing provides perspective, says Paul J. Rosch, M.D., president of the American Institute of Stress in Yonkers, NY. Divide a piece of paper into two parts. On the left side, list the stressors you may be able to change, and on the right, list the ones you can’t. “Change what you can,” Dr. Rosch suggests, “and stop fretting over what you can’t.”
8. Count to 10
Before you say or do something you’ll regret, step away from the stressor and collect yourself, advises Dr. Cooper. You can also look away for a moment or put the caller on hold. Use your time-out to take a few deep breaths, stretch, or recite an affirmation.
9. Switch to Decaf
Wean yourself slowly, or you might get a caffeine-withdrawal headache that could last for several days, cautions James Duke, Ph.D., the Fulton, MD, author of The Green Pharmacy (Rodale Press, 1997). Subtract a little regular coffee and add some decaf to your morning cup. Over the next couple of weeks, gradually increase the proportion of decaf to regular until you’re drinking all decaf. You should also consider switching from regular soft drinks to caffeine-free ones or sparkling mineral water.
10. Just Say No
Trying to do everything is a one-way ticket to serious stress. Be clear about your limits, and stop trying to please everyone all the time.
11. Take a Whiff
Oils of anise, basil, bay, chamomile, eucalyptus, lavender, peppermint, rose, and thyme are all soothing, say Kathy Keville and Mindy Green, coauthors of Aromatherapy: A Complete Guide to the Healing Art (Crossing Press, 1995). Place a few pieces of rock salt in a small vial, then add a couple of drops of the oil of your choice (the rock salt absorbs the oil and is much less risky to carry around in your purse than a bottle of oil). Open the vial and breathe in the scent whenever you need a quick stress release.
When thoughts
Of the last bitter hour come like a blight
Over thy spirit, and sad images
Of the stern agony, and shroud, and pall,
And breathless darkness, and the narrow house,
Make thee to shudder and grow sick at heart;--
Go forth, under the open sky, and list
To Nature's teachings. . .
"Thanatopsis", William Cullen Bryant
[As recently reported in the New York Times.] "Scientists have known for some time that the human brain’s ability to stay calm and focused is limited and can be overwhelmed by the constant noise and hectic, jangling demands of city living, sometimes resulting in a condition informally known as brain fatigue.
"With brain fatigue, you are easily distracted, forgetful and mentally flighty — or, in other words, me.
But an innovative new study from Scotland suggests that you can ease brain fatigue simply by strolling through a leafy park.
"The idea that visiting green spaces like parks or tree-filled plazas lessens stress and improves concentration is not new. Researchers have long theorized that green spaces are calming, requiring less of our so-called directed mental attention than busy, urban streets do. Instead, natural settings invoke “soft fascination,” a beguiling term for quiet contemplation, during which directed attention is barely called upon and the brain can reset those overstretched resources and reduce mental fatigue.
"But this theory, while agreeable, has been difficult to put to the test. Previous studies have found that people who live near trees and parks have lower levels of cortisol, a stress hormone, in their saliva than those who live primarily amid concrete, and that children with attention deficits tend to concentrate and perform better on cognitive tests after walking through parks or arboretums. More directly, scientists have brought volunteers into a lab, attached electrodes to their heads and shown them photographs of natural or urban scenes, and found that the brain wave readouts show that the volunteers are more calm and meditative when they view the natural scenes."
13. Do a Good Deed!