Thousands hit the streets for NYC Marathon as New Yorkers cheer on runners across five boroughs

And today is the 50th anniversary of the New York City Marathon, and runners are taking part. One change you need to know about the big race is altering its Bronx route for the first time in 15 years. The updated route takes runners farther along Alexander Avenue before turning onto East 141st Street, and then 3rd Avenue. And among the runners this year is Dr. David Schlesinger, a 63-year-old Long Island man who suffered what's known as a widow. Make a heart attack just three weeks before he was set to run the race two years ago. I made it my mission when I was told that I would never run again, you know, to prove the doctors wrong. There has not been a day over the last two years that I have not thought anything other than this, you know, experience. And it starts from the cannon going off on the Verrazzano Bridge, you know, with 50,000 plus runners, you know, yelling, cheering and screaming. Doctors say this type of heart attack has a 92% mortality rate if not treated within 90 minutes. Schlesinger got a life-saving stent at minute 81.