The 29-year-old Coxheath mother was left fighting for her life after going into cardiac arrest at Maidstone Leisure Centre.
The day should have been a day like any other when Genna and friend Danielle Senior went for a gentle swim.
Genna and Graham Kelly on their wedding day, weeks after Genna’s heart attack
But within minutes of getting in the water Genna, who was unaware she had health problems, collapsed.
Danielle grabbed her unconscious body and screamed for help, sending lifeguards rushing to get the centre's defibrillator.
This vital piece of life-saving equipment was used to shock Genna's heart back into a regular rhythm.
"My life changed forever that June day, but if I can get all of the negatives out of the way and do something good then I will..." - Genna Kelly
Medics put her in an induced coma and she was taken to the William Harvey Hospital in Ashford, where she remained unconscious for two days before being transferred to St Thomas' Hospital in London.
There, she went through three operations, including having a pacemaker fitted in case the same thing should happen again.
Amazingly Genna, who has sons aged eight and five, was able to marry long-term partner Graham just two-and-a-half weeks after being discharged from her five-week stay in hospital.
Now seven months later, as she continues to undergo tests to find out what caused her heart attack, she is determined to save the lives of others by fundraising for defibrillators to be kept in more public places.
She said: "My life changed forever that June day, but if I can get all of the negatives out of the way and do something good then I will."
Her first goal is to get one for her sons' school, St Francis in Queens Road, Maidstone.
She will be holding a fundraising event on Friday, January 31, in Park Wood and is appealing for donations of prizes that can be taken to the school.
St Francis's acting head teacher Elisabeth Blanden said a non-uniform day had already been held to generate cash, which would be matched by the Friends of St Francis.
She added: "It had never occurred to us before this happened to Mrs Kelly that we should have a defibrillator in the school. We are supporting the fundraising as much as we can."