The 70-year-old is part of a project called Streak Runners International, where members pledge to run at least a mile every single day - and Sandra recently passed the 500-day milestone.
She said: “I’ve had a handful of aborted streaks over the past two or three years, so I guess you could say that it was something of a relief to reach the 500 mark.
“Next up is what the streak running community refers to as Comma Day, when you reach 1,000. Of course, that is still more than a year away.”
She only started running six years ago, at the age of 64, while living in America, where the SRI scheme originates.
“It was a New Year’s resolution, not to run, particularly, but to lose a bit of weight,” she said. “I wasn’t seriously overweight, but I’d found that the older I got, the harder it became to keep the pounds off.
“At the time, I was living in Florida and was lucky to have a house that sat on a disused golf course, so I had approximately 10km of golf cart track to run on.”
From a slow and steady start, Sandra built up her stamina and after moving back to Yorkshire, she decided to start her current daily challenge in July 2016.
“My partner and I are avid auction goers, and I was lucky enough to pick up a treadmill for only £25, so on the days that my old bones don’t feel like hitting the pavement, I can run on the treadmill while watching the cricket that I’d sadly missed during my time in the US.”
A mile is the absolute minimum she clocks up each day, and Sandra regularly completes longer distances.
She is a regular at the Sewerby Parkrun 5kms on Saturday mornings, where her best time is around 30 minutes.
In 2016, Sandra ran her first marathon in York, which was a qualifying event for an age-related England Athletics marathon team and she was selected to represent them at the Chester Marathon last October.
Later this year, she is going back to America for the the inaugural Alamo marathon in San Antonio.