"The first time you do it," Reynolds, speaking about his high-flying stuntwork, tells the new issue of Entertainment Weekly, "you're deeply considering an adult diaper."
In the movie, Reynolds plays Hal Jordan, an arrogant but gifted test pilot recruited to become an intergalactic super hero. To look the part of a DC Comics super hero – he sports a sexy, tight green outfit – Reynolds launched into a lean diet.
"You spend one day a week eating what you want and the other six days eating drywall and woodchips," he said, presumably joking.
During shooting, Reynolds, 33, was uncomfortably strapped into a snug wire harness for his flying scenes – not that comic-book hero territory isn't already familiar to the star, who played the chatty hitman Deadpool in 2009's X Men Origins: Wolverine.
"It's all part of the job," says Reynolds. "So I guess I can't complain."