When you exercise, however, your working muscles demand greater amounts of oxygen and you create more carbon dioxide waste as a result. This results in an automatic increase in your respiration rate. But exercisers—especially new ones—shouldn't take this process for granted. Becoming more aware of your breath can help you feel more comfortable (breathing too slowly can increase your heart rate and affect your perceived intensity), prevent complications (like dizziness or faintness that can result from a lack of oxygen), and get more out of your workouts. Here's what you need to know to breathe properly during five common types of exercise.