Let's say he would have never known that he's good at running, or simply didn't believe in himself, and he would have never trained a day in his life.
Let's say he would have become a farmer in his hometown and lived a peaceful, random farmer life.
And then one day, on a Wednesday, he learns that on Sunday there's a 5k race, and he decides to run it for fun.
He's not injured, and he's not overweight.
At age 25yo.