Alison Dempsey wants to transform her own life to help her son Jack (14), who suffers from cystic fibrosis.
She is one of four finalists from the capital who is in the running to be a leader on the new series of Operation Transformation.
The Raheny woman is already heavily involved in her local community and has three other children.
"I want to stay healthy; I don't want to die young," the 45-year-old who weighs 15 stone said.
"I have four kids and a lot to live for. I just want to stop having regrets", said Alison.
Another contestant, Carl Grogan (23) from Ballyfermot, is hoping to shed the weight he gained after losing his job in March.
He weighs 15 stone but wants to make the cut as a leader this year after failing to make it past the final 24 last year.
Carl has put on at least a stone and a half since last year and wants to make the final five this year.
"I lost my job and fell into a rut. I was sitting at home, eating breakfast rolls and ordering take-aways."
Dad of four Gavin Walker (35) is starting over following the breakdown of his marriage, but feels that his weight is preventing him from moving on.
"I know who Gavin the father is ... but I don't know who Gavin is any more," said the 18-stone process technician who is from Tallaght but now lives in Kill, Co Kildare.
Mother of two Leanne Reddy (27) is eager to lose the weight to be able to keep up with her young children.
"I want to be get active again and be able to go out and play with my kids.
"So it's for me and my family," said the stay-at-home mum who is from Dublin, but now lives in Portlaoise.
The four Dubliners are among 19 finalists hoping to be chosen as a leader on the sixth series of Operation Transformation.
The nation will watch as the chosen five leaders go under a new fitness and diet regime next January.