Not only is she 80 this year, and still going strong, but the Leeds-based charity now runs two orphanages in Kenya, helping look after more than 100 children.
And Mabel, who is the pastor at the Bethel United Church on Victoria Road, Hyde Park, is about to travel to the country to visit the orphans and hand over vital medical supplies.
Kost aims to provide shelter, food, education and medicine to Kenyan orphans at two bases in Homa Bay and Rapedhi Lwala.
Mabel said: "The children we're looking after have got nobody left, or just extended families that can't afford to look after them, so they end up begging on the streets.
"One boy had heard about Kost and walked 20 miles by himself to Homa Bay to get help.
"The work of the charity is absolutely vital and there are so many needs out there that we cannot meet them all.
"I've seen the suffering first hand - you can't come home and not do anything."
Kost relies on sponsorship, fundraising and donations and is run entirely by volunteers so that every penny raised can go towards helping Kenyan orphans.
Next month, Sarah Mollitt is running the London Marathon in aid of the charity with mum Lillian, who used to live in Kirkstall.
Dedicated
She said: "With Kost, the money I'm raising is going virtually directly to the children who really need it. "They've lost their parents to HIV and AIDS which is really, really sad and many of them are living on the streets with nobody to help them.
"The volunteers are so dedicated and it's a struggle for the charity to survive every year. If these volunteers don't raise the money, the orphanages will close – it's as cut and dried as that."
l To support Kost or for more information on the charity, call Gill Waterhouse on (0113) 269 5977.
suzanne.mctaggart
@ypn.co.uk