Take a timer and practice the 5.5 rule: 5.5-second inhales followed by 5.5-second exhales.
Most doctors will tell you that a normal breathing rate is anywhere between twelve and 20 breaths a minute, with an average intake of about half a liter per breath. But breathing less and breathing slower are beneficial to your health. When breathing at the ‘normal’ rate, your lungs absorb about a quarter of the available oxygen in the air. You exhale the rest back out. By taking longer and slower breaths, you allow our lungs to soak up more oxygen.