Take a deep breath before you blow out your birthday candles! If you're like most people, you probably never even think about breathing—you just do it. Inhale. Exhale.

For people with asthma, however, breathing can be difficult. Asthma is a lung condition in which the muscles around the airways get very tight. The airways may fill with thick mucus. People having an asthma attack have a hard time getting enough oxygen into their bodies.