Ryan Reynolds showed millions of fans the importance of getting a colonoscopy.

The actor said he lost a bet and agreed to record his experience getting the procedure. The 45-year-old posted the video on Instagram.

After the procedure, Reynolds' doctor informed him that a polyp was found.

"This was potentially lifesaving for you," Dr. Jonathan LaPook said. "I'm not kidding. I'm not being overly dramatic."

LaPook said he removed the polyp, which could have led to colon cancer.

"This saves lives pure and simple," he said.

The U.S. Preventive Services Task Force recommends that adults aged 45 to 75 be screened for colorectal cancer.

Colorectal cancer is the fourth leading cause of cancer-related deaths in the U.S., according to the Centers for Disease Control.