Following the “Saturday Night Live” 40th anniversary special that aired Sunday night, comedian and SNL veteran Kevin Nealon is opening up for the first time about something a lot more serious— his heart condition, atrial fibrillation (AFib).

While vacationing in Mexico, Nealon experienced his first symptoms of AFib.

“My heart started running away, like a pack of horses,” Nealon said. “Then it slowed down and became irregular.”

According to the American Heart Association, AFib is a quivering or irregular heartbeat (arrhythmia), that can lead to blood clots, stroke, heart failure, and other heart-related complications. The organization estimates that there are 2.7 million Americans living with AFib, making it the most common serious heart rhythm abnormality in people over the age of 65.

Because AFib patients are more susceptible to blood clots, their risk of stroke is increased by five times— AFib accounts for 15 to 20 percent of all strokes. However, according to a 2009 study, only 33 percent of AFib patients think it is a serious condition.

“I always tell people if you think you are susceptible to a blood clot, go check with your doctor,” Nealon told Dr. Manny Alvarez, Fox News Channel’s Senior Managing Editor for Health News. “Check out what the risks and the benefits are and see what's right for you.”

For February’s American Heart Month and March’s Blood Clot Awareness Month, Nealon has teamed up with Janssen Pharmaceuticals and legendary golfer Arnold Palmer to share his story, raise awareness, and aims to make to a difference in the lives of the millions of people suffering from heart disease.

Nealon shared his story in a video on Drive4Clots.com.

For every individual who views the video, Janssen will make a donation to Mended Hearts, a non-profit organization that helps heart disease patients and their families and caregivers through visiting programs, support group meetings, and educational forums.

Nealon hasn’t let his diagnosis get in the way of his life, though. In addition to travelling the country performing stand-up comedy, he is starting the second season of his AOL series, “Laugh Lessons with Kevin Nealon.”

Click here for more on Kevin’s story and to contribute to Mended Hearts.