January 1, 1991 was a date that changed Alan Robinson's life forever.

After a night of drinking, Robinson got into his car to drive home. He didn't make it very far.

"I knocked down two light posts and hit the viaduct, and that was it. I wanted to get out of the car. But I couldn't even move," he told Chicago's WGN 9.

Robinson was declared an "incapable quadriplegic” after the accident. He sustained an incomplete spinal injury in the neck that left him partially paralyzed in all four limbs.

As he recuperated, Robinson said he communed with God.

"I basically knew that He wanted me to run marathons,” Robinson said. "When you have a vision with God, the only thing you can really say is okay."

Running when you're a quadriplegic isn't just hard; it's supposed to be impossible.

"I’m not even supposed to be standing up, let alone walking or running a marathon,” he said.

But Robinson wasn't about to let that stop him.

He began working hard at walking, then at running. And in 2003, 12 years after his crash, Robinson completed his first Chicago Marathon in just over six hours. 

Since then he's ran the Chicago Marathon 10 more times, and the Boston Marathon four times, as well as a few ultra-marathons.

According to ABC 7 Robinson was hoping to complete his 20th — and final — marathon in Chicago on Sunday, October 8.

With a team of assistants at his side, Robinson began the 40th Chicago Marathon at 7:30 am, and stopped around 11 pm at the 18-mile mark. He planned to finish the remaining 8.2 miles the next day, October 9.

Robinson was forced to make this race his last due to several conditions. 

He is battling prostate cancer, and was recently diagnosed with a heart condition called cardiac amyloidosis. Also known as "stiff heart syndrome," the condition forced Robinson to make frequent stops during his race.

His doctors weren't so sure running with the condition was a good idea. 

"What he has overcome is miraculous,” Dr. Danjiv Shah, Robinson's cardiologist at Northwestern Memorial Hospital, told WGN. "Right when you meet the guy, he's got some infectious quality about him and you really get close to him. All of us here really have come to be fond of him, and I think we worry about him running the marathon with his heart condition."

But, again, Robinson wasn't going to let what medical science said stop him from achieving his goals.

Back in July during training, Robinson credited God for pushing him to keep on.

"Do I know what the result is going to be? No. But what I know is that I have to keep doing it because I know that is what God wanted me to do."

Robinson's overcome not just his injuries, but memories of his time in Vietnam and both alcohol and drug abuse to get where he is today.

And he knows that he can be a symbol of redemption and the power of determination. 

"By me running, I inspire other people," he said. "By me running, I'm doing what God wanted me to do."