"An hour after [I finished], I thought I would have to go to the hospital," Reynolds, 32, reveals in the March issue of Men's Health, on sale Feb. 10.
Just days before participating in the marathon – the Canadian actor's first – he fell ill. But within just a few miles, he says, he was bolstered at the sight of Michael J. Fox, on whose foundation's behalf he was running. (Reynolds's father, Jim, has lived with Parkinson's disease for the past 15 years.)
"I finished 30 minutes faster than I thought I would," he says.
Scarlett, No; Motorcycles, YesWhile Reynolds detailed his marathon experience, he wouldn't delve into his relationship with wife Scarlett Johansson, 24, whom he wed last fall.
But he did discuss another of his passions: motorcycles.
"I just like to cruise … I love the fact that on a motorcycle, riding a motorcycle is the only thing you're doing," says Reynolds, who rides a Triumph Bonneville and a new Paul Smart Ducati.
"We're constantly connected to information and stimulation. On a bike, there's none of that. It would take an extremely talented imbecile to send a coherent email from a motorcycle at 80 m.p.h."
On the Road AgainThis summer, Reynolds, one of his brothers and a friend will hit the road in Alaska for a ride on the Top of the World Highway.
Despite suffering wipeouts in the past, he says, he's not scared: "There's an old expression: There are two kinds of riders – those who have gone down, and those who are going to go down. I've already gone down a few times."