"Because I'm alive, that's why."
That was the only reason John Beagle needed to hit the pavement on Sunday.
At 83, he was the oldest person to take part in The Canberra Times 2015 Fun Run.
Mr Beagle first ran the 10-kilometre course in 1976, aged 44, in 38 minutes.
This year, he finished it in 80 minutes.
"I never push myself because at my age I'm interested in wearing out not rusting out and I don't intend to stuff myself in the process," the Weetangera local said.
"As you get older, you cannot afford to be comfortable. Comfortable is a recipe for disaster, it gives you all sorts of ailments and you end up in the hands of doctors. Who wants to end up there?"
Mr Beagle founded the very first jogging club in Canberra and recently completed The Sun-Herald City2Surf in Sydney.
He works out at the Australian Institute of Sport gym three or four times a week and on the days in-between he takes long walks or runs, or works out in his home gym on his back verandah.
His wife Kay said he's "almost addicted" to health and vitality, especially for older people.
"He feels we have a responsibility to ourselves and to the community to keep fit and not be a burden on society and he's just going to keep going," Mrs Beagle said.
"I can't keep up with him but I'm always at the finish line with the warm clothes. He's an inspiration for young and old."
The seasoned runner said he didn't mind being overtaken by some of his younger competitors. ln fact, he wished more young people would give fun runs a crack.
"I'm delighted that they're getting off their arses and running. So many others don't," he said.
"The people of the younger generation are going to pick up the tab for massive medical expenses [if they don't prioritise their health]."