When was the last time you thought about breathing? Most people usually do not. When we are healthy, breathing happens naturally and easily. Without much effect on our part, the human respiratory system works hard.

When you breathe deeply, the air coming in through your nose fully fills your lungs, and the lower belly rises. On its website, Harvard Medical School notes that deep breathing may slow the heartbeat, lower blood pressure and lower stress. Deep breaths help your body fully exchange incoming oxygen with outgoing carbon dioxide.

However, many people do the opposite of deep breathing. They take short breaths and have shallow breathing. Experts call this “chest breathing.” Shallow breathing limits the expansion of the diaphragm and its movement. The lowest part of the lungs does not get a full share of oxygenated air. This can make you feel short of breath and worried, or anxious.

Several health websites explain an easy deep breathing exercise.

Find a place to sit or lie down. Place one hand just below your ribs. Take a slow, deep breath — or inhale — through your nose. Feel your hand go up. Your stomach should rise and expand. Now breathe out slowly through your mouth. Make sure to breathe out — or exhale — all the way. Feel your hand and stomach go down.

The American Lung Association website states that if done repeatedly, breathing exercises can help remove stale air from the lungs. This will increase oxygen levels and get the diaphragm to return to its job of helping you breathe.