While dining at an outdoor Orland Park restaurant last Sunday, the boy stopped breathing and collapsed.
What happened next had everything to do with fast action, good medical training and fate.
Nicholas Theilgaard, 16, doesn't remember much about last Sunday except what everyone is now telling him - that he almost died.
He composed a rap song to celebrate his survival and the people who helped save him.
"Take a drink, put it down, I go whoa. . . that felt kinda weird. . . that's all I remember," said Theilgaard.
"He turned purple and blue and I knew I had lost my son," said Diane Theilgaard, mother.
Theilgaard collapsed while eating lunch in the outdoor area of a restaurant in Orland Park. His heart had stopped beating.
Sarah Kane, a nurse practitioner, also happened to be dining at the same time.
She and her fiance, a physician, jumped into action and immediatly started CPR on the unresponsive teen.
The hospital did not have an automated external defibrillator nearby, so they kept doing chest compressions, keeping him alive for about 10 minutes until paramedics arrived.
"I told them he really needs an AED, he needs to be shocked, don't do anything else, let's go, like get it moving," said Kane.
Kane works at Advocate Children's Hospital in Oak Lawn, the same hospital where Theilgaard already happens to be a patient.
The teen was recently diagnosed with a rare heart condition that causes the heart muscle to slowly change into fatty tissue and to scar. This can lead to abnormal rhythms.
But until Sunday, his heart seemed to be doing alright.
"All of his screenings have been fairly benign looking. . . so it did come as a shock," said Dr. Ira Shetty, pediatric cardiologist, Advocate Children's Hospital.
"It was just amazing that Sarah was there and to think that she works here with my cardiologist- unbelievable," said Theilgaard.
The thankful teenager is now wearing a special vest 24-7 to monitor his heart. And if necessary, it can deliver more lifesaving shocks if his heart is in distress.
Next month he will be implanted with a heart defibrillator. Kane kiddingly says Theilgaard owes her a chicken sandwich. Neither she nor her fiance ever finished their restaurant meals.