Danny Silk, 38, of Chapel Allerton, wanted to take part in the 100 Miles in a month 2020 challenge to raise cash for a worthy cause.
But he couldn't decide on just the one charity to help and instead opted to double the challenge to support two charities.
Danny, who is the founder and director of charity the LGBT+ Sport Fringe Festival, will have to complete around six-and-a-half-miles per day to reach his goal of 200 miles by the end of August.
He wants to raise as much money as possible for the Bone Cancer Research Trust and Teenage Cancer Trust.
Danny, who works as a personal trainer in Leeds, said: "A lot of my clients are running with me as well, to motivate me and keep my energy and enthusiasm up."
Click here to donate to Danny's appeal for the Bone Cancer Research Trust and click here to donate to his appeal for Teenage Cancer Trust.
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