You could save a life by knowing how to perform cardiopulmonary resuscitation, or CPR. We’ve recently witnessed how prompt medical attention, including the use of both CPR and an automated external defibrillator (AED) saved the life of NFL’s Damar Hamlin after he suffered cardiac arrest on the football field. CPR helps restart the heart and without it, a person in cardiac arrest can die in minutes, according to the Centers for Disease Control and Prevention (CDC).

“You are alive because you are breathing and your heart is beating,” Dr. Georgios Syros, a leading cardiologist from New York affiliated with Mount Sinai Hospital, tells TODAY.com. “If your heart stops beating, you don’t have blood going to the brain. When a person’s heart stops beating, CPR is a mechanical way to (temporarily) take over the job of the heart and lungs.”

While one survey found that 54% of people said they know about CPR, only 10% said they know how it is performed. An estimated 90% of people who experience cardiac arrests outside a hospital die, but if someone performs CPR in the first few minutes, the odds of survival double or even triple, says the CDC.

Both the American Red Cross and the American Heart Association offer training classes.

The American Heart Association gives the following guidelines for an untrained lay person to perform Hands-Only CPR. Hands-Only CPR has been shown to be as effective as conventional CPR with breaths when needed to be performed at home, work or in public. Hands-Only CPR includes just two easy steps:

1. If you see a teen or adult collapse, first call 911.
2. Push hard and fast in the center of the person’s chest at a rate of 100 to 120 beats per minute. Examples of songs with this beat include “Stayin’ Alive” by the Bee Gees, “Hips Don’t Lie” by Shakira or “Walk the Line” by Johnny Cash.

If a person is talking and breathing, they don’t need CPR, but if they are fine one minute and then collapse or are unresponsive when you talk to them or tap them, or are not breathing, it’s time to act.

If you see a person is choking, the first thing you should do is perform the Heimlich maneuver to clear the airway, says Syros. “If that fails and they lose consciousness, call 911 and then do CPR.”

A video of Hands-Only CPR can be found on the American Heart Association website.