As if Henry Cavill wasn't muscular enough as DC's Man of Steel, he recently spent a lot of time at the gym to become the impossibly-chiseled Geralt in Netflix's The Witcher. Cavill got so jacked that his muscles constantly busted through his costumes, and now he's putting his fitness to good use by running to benefit the Durrell Wildlife Conservation Trust and help save endangered species from extinction.

Becoming Even Bigger Than Superman

In order to portray The Witcher's Geralt, Cavill improved upon his Superman musculature and spent countless hours training at the gym. He even worked with Dave Rienzi, a bodybuilding expert who trains Dwayne "The Rock" Johnson.

Reviews for The Witcher, which premiered on Netflix last December, have been mixed, but with a potential second season in mind, Cavill is already back to training.

A Costume Designer's Worst Nightmare

While Cavill's bulging muscles helped attract viewers to The Witcher, his hulking frame made things incredibly difficult for the show's costume designers.

"Not only was the actor particular about his outfit, but that during shooting, his muscles wore down the leather at such an alarming rate that replacements were constantly produced to meet the production's needs," Tim Aslam, The Witcher's costume designer, told Polygon.

Related: 20 Behind The Scenes Pics Of The Witcher That Change Everything

Cavill Is Putting His Training To Good Use

While much of Cavill's focus on the gym has been on becoming stronger and more muscular, he's now starting to work more on his cardio as well. The 36-year-old actor will be participating in The Durrell Challenge, a 13k race to benefit the Durrell Wildlife Conservation Trust, one of his favorite charities.

The trust works to save endangered species from extinction, and Cavill told fans on Instagram that his double training is now not only for The Witcher season 2, but "for all the ecosystems of the world" as well.

The 8-mile race will take place in Jersey in the UK on May 17. Fans looking to "toss a coin to their Witcher" and donate can sign up at doitfordurrell.com.

Next: 20 Little Known Facts About The Witcher's Henry Cavill