For even the fittest of people the propect of rowing, cycling and running 15km would be a daunting task.
But for one 78-year-old the distance provided a healthy challenge which saw him get to the finishing line in just over one hour.
David Lamburn raised more than £1,000 for charity after he completed the multi-skilled exercise at a gym in the Nene Centre in Thrapston on Monday.
Mr Lamburn, who lives in Oundle Road in Polebrook, said: “The challenge was hard but left me with a wonderful feeling when I finished.”
The former serviceman took on the task to mark his 78th birthday.
He aimed to complete it within 78 minutes – but did it in 71.
It marks a remarkable turnaround for the man, who aged 38 woke up one morning with the intention to get fit.
He said: “As part of my military pension I received a report which called me obese.
“The comment shocked me, but made me realise the unhealthly life I was leading.
“I was smoking 10 cigarettes a day, drinking too much whisky and doing no exercise.
“I dropped the cigarettes and drink and decided to get myself fit.
“Today I do exercise two to three times a week – I feel brilliant.”
In completing the task, Mr Lamburn raised £1,200 for the Thorpe Hall Hospice run by Sue Ryder Care.
He chose to raise the money after a friend who died of cancer stayed there.
He also wants the money to be used to help people decide where they die.
To sponsor Mr Lamburn, call 01733 330060.