Jon has rowed for Great Britain and has completed four marathons.
A student from the University of Bath is going green as he trains for the Barcelona Challenge triathlon.
Jon Alexander, 27, wants to become the greenest ever Ironman when he takes part in the event on Sunday, October 4.
He will set aside conventional sports gear for the gruelling challenge, instead aiming to use a bamboo bike and shoes made from recycled fibres.
Jon hopes to motivate athletes to get involved in the environment, and sports companies to take a greener approach.
Jon aims to cycle 112 miles on his bamboo bike, run 26.2 miles in shoes made from recycled fibres and swim 2.4 miles in an eco-friendly limestone-based rubber wetsuit.
He hopes to complete his first triathlon in under 12 hours.
Jon said: "I believe all athletes are environmentalists at heart, if you define environmentalists as people who love the natural world.
"But we fly all over the world, we burn through a load of food, and we use a huge amount of specialist gear - all without really appreciating what we're doing to the places where we love to train.
"We don't even put pressure on suppliers. I've found a couple of small companies who are doing things differently but there's real lack of take-up in the sports world."
Jon doesn't feel that his green approach will compromise his performance and says that bamboo bikes have even been shown by several US athletes to improve performance over a long ride.
Jon is raising funds for the Wilderness Foundation, a charity which works to use wilderness experiences to help young people develop an emotional connection with the natural world.
For more information, you can check out Jon's blog at