I've discussed adopting healthy eating habits and realistic exercise as ways to change your lifestyle. But there's a simple activity you can do to bring on positive feelings that will enhance all your other efforts along the road to well-being.

Breathing. We do it constantly and never give it a second thought. If we're still alive, we reason, we must be doing it right. Well, yes and no. We all breathe, but most of us don't do it as efficiently as we could, and few of us are aware that you can alter your mood simply by how you breathe. For centuries, students of hatha yoga have known what Western medicine is just beginning to discover: Much of how we feel depends on how we breathe. Here is a yogic breathing technique you can master in just a few minutes and practice anywhere, anytime.

Why does it work? Researchers have shown that any form of controlled, conscious breathing – whether the subjects breathe at a rate of fifteen, six, or three breaths a minute – substantially increases the level of oxygen in the blood. Heart patients in one study also performed better in tests that measured their response to exercise.

This breathing exercise is best done with your tongue in the yogic position: Touch the tip of your tongue to the back of your upper front teeth, and then slide it up until it rests on the ridge of tissue between your teeth and the roof of your mouth. Keep your tongue there for the duration of the exercise.

The Relaxing Breath
The key to doing this exercise is pacing your breathing so that the relationship between the time you inhale, hold your breath, and exhale strictly adheres to the ratio 4:7:8, as outlined below. You want to be sure that it takes you twice as long to exhale as it does to inhale. The speed at which you're breathing isn't important. Don't hold your breath, beyond what feels comfortable to you. Over time, you'll be able to hold it longer. For now, though, concentrate on maintaining those ratios.

Begin practicing this exercise at least twice a day: Right after waking, right before bedtime, and before meditating are all good times. Feel free to set other times, perhaps right after you get into the car, step out of the shower, or board the train for the commute home after a long day at the office.

1. Sit or lie comfortably with your back straight. Place your tongue in the yogic position. Exhale completely through the mouth, making an audible whoosh sound. 
2. Close your mouth tightly: Quietly inhale through your nose to the count of 4. 
3. Hold your breath for the count of 7.
4. Exhale audibly through your mouth to the count of 8. If you have difficulty exhaling with your tongue in the yogic position, try pursing your lips. 
5. Repeat steps 2 through 4 three more times, for a total of four cycles. Breathe normally and observe how your body feels.

Wake Up Tired Eyes
Place a few metal tablespoons in the refrigerator until they’re chilled – at least half an hour. Whenever you need to feel refreshed, lie down in a quiet spot, gently place the spoons over your closed eyes, and focus on something that makes you feel happy and relaxed. The rest will refresh you, and the cool spoons will reduce puffiness