Ken Bania, of Queenstown, died in April after a 16-year battle with follicular lymphoma.
The keen runner and former New Yorker had always encouraged his son to get into the discipline, but the TVNZ reporter said his job had often got in the way.
However, when he returned from an overseas trip in May last year after spending six weeks eating and drinking, his father said to him: ''I look forward to seeing you a shadow of your current self in the near future''.
''It was all the motivation I needed to take my running more seriously. Since then, I've lost 12kg and haven't looked back.
''He'd always give me a bit of stick for not being much of a runner, which I think was his way of encouraging me to get into it.''
Mr Bania said his father was incredibly determined and single-minded, which showed in his battle with cancer. It also helped him complete 14 marathons, many in under three hours.
When Mr Bania signed up for the Dunedin Marathon, to be held on September 8, his father was his main motivation. He hoped to raise money for cancer research, as well as Dunedin Hospital, where his father was treated for many years.
Since April, he had run tracks in Dunedin and Queenstown, where his mother, Margie Bania, lived, and on occasions he would hit the treadmill.
''Undoubtedly, running through the Otago winter has been the hardest thing. There have been a few times I've been out running and lost all feeling in my hands and arms.''
Mr Bania wanted others to know that almost anyone could run a marathon and it was about starting to train with small reachable goals and not making drastic changes overnight.
''Running is an incredibly rewarding experience and you certainly never hear people talking about how much they regret running a half or full marathon.''
Mr Bania hoped one day to compete in the New York Marathon - something his father always wanted to do.
The only glitch was the need to cut an hour off his estimated sub-four-hour marathon time to qualify. Donations for the cancer fundraiser can be made to the Ken Bania Appeal Account, BNZ 02 0948 0290006 25.