Nearly four decades ago, musician Roger Hillsdon swapped a life of late nights, parties and drinking for running.

Now 75, he has run 23 consecutive Sydney Morning Herald half-marathons and will be one of the oldest competitors in this year's race.

While Mr Hillsdon sings to himself as he runs, he also credits running as helping him to keep singing.

"A lot of musicians have found that because it's not always a healthy lifestyle, if you want to keep playing music at my age and still be able to do those things, you need to be pretty fit and healthy," he said.

Mr Hillsdon, who has played with rockers including Johnny O'Keefe, Col Joye, the Joye Boys and Billy Thorpe, said he still runs up to 10 kilometres most days.

"I love to go for a run but the competitive thing is not that easy any more. As you get a bit older, you get a bit slower and each year it becomes a little bit harder but I will keep running as long as I can," the Georges Hall resident said.

It was a doctor's warning that he could either get fit or face serious illness that prompted Mr Hillsdon to go on his first run at the age of 40.

"I ran about 2km and when I came back I was so giddy I had to sit on the footpath. I thought 'I might have to take this a bit more seriously'."

After taking up the hobby seriously, Mr Hillsdon said he cut down on the rock and roll lifestyle although he continued to play gigs and run a music store.

"Unfortunately, a lot of my friends in bands that I have worked with over the years didn't go down the exercise route. They carried on doing what they were normally doing. Not everyone finds running fun, but it certainly helped me to continue playing," he said.

For those feeling inspired, he recommends Rihanna, Kanye West and Paul McCartney's collaboration as a good running song.

The Sydney Morning Herald Half Marathon will be held on Sunday, May 17. For more information click here.