Donovan, who has been a patient of Dr. Schmitt's for several years, suffered a mild heart attack in 2010, followed by three episodes of cardiac arrest within a 24-hour period in 2012.
With Dr. Schmitt's care, Donovan has not only survived, but thrived.
"Since 2012, I've run five full marathons and probably 32 half marathons," said Donovan, who has since been surgically implanted with stents, a pacemaker and a defibrillator.
Dr. Schmitt and Donovan first ran the half marathon together last year, and will do so again Saturday morning.
"He said if I can do it, you can run it," said Dr. Schmitt.
Dr. Schmitt said Donovan is a model patient and an inspiration. "[It is] extremely rare to come across someone like him that's just really impressive, disciplined," said Schmitt.
Schmitt advises all cardiac patients to not only listen to their doctors but also to their bodies, watching out for warning signs and staying active.
"I don't think everybody should run half marathons or marathons like Bill did -- certainly the exception -- but you should exercise on a regular basis," said Schmitt.
"I'm healthy and ready to go," said Donovan, when asked how he's feeling about the race.
Donovan and Dr. Schmitt will be part of a team raising money for the Pat and Jim Calhoun Cardiology Center at UConn Health in Farmington.