You don't need to fall into the stress mode of life. You can use breath to relax, rather than stress, your mind and body. Yoga helps you to relearn that natural state that your body and mind want to be in: relaxation.
Deep breathing is both calming and energizing. The energy you feel from a few minutes of careful breathe is not nervous or hyper, but that calm, steady energy we all need. Slow, steady, and quiet breathing gives a message to your nervous system: Be calm.
Whole books have been written on yoga breathing. Here is one 5-minute Breath Break. (Read through the instructions several times before you try the practice.)
1. Sit with your spine as straight as possible. Use a chair if necessary but don't slump into it. Feet flat on the floor with knees directly over the center of your feet. Use a book or cushion under your feet if they do not rest comfortably on the floor. Hands are on the tops of your legs.
2. Close your eyes gently and let them rest behind closed lids.
3. Think about your ribs, at the front, back, and at the sides of your body. Your lungs are behind those ribs.
4. Feel your lungs filling up, your ribs expanding out and up. Feel your lungs emptying, your ribs coming back down and in. Don't push the breath.
5. The first few times you do this, do it for 2 to 3 minutes, then do it for up to 5 to 10 minutes. At first, set aside a time at least once a day to do this. When you learn how good it makes you feel, you'll want to do it at other times as well.
Just as one stressful situation goes into your next challenge, relaxing for a few minutes every day gradually carries over into the rest of your daily life and activities.