Beating cancer for a second time, the fighter from the Tyne Valley started running to help her lung function better after one third of it needed to be removed as she wanted to continue playing the flute.
Years down the line, she stood proudly on the podium at the International Triathlon Union Long Distance Duathlon World Championships in Zofingen, Switzerland, just this weekend as she impressed to take bronze in the 55 to 59 age category.
Having previously won medals at short distance events, she decided to go that little bit further and take on the 10km run, 150km bike ride and 30km run.
To earn her place in Switzerland, Rosemary completed the long distance course in the Battlefield Duathlon, in Northamptonshire, in a standard time for the GB vest.
The course at Zofingen has became famous across the globe as it is regarded as one of the most severe routes in the competitive circuit as it rises to nearly 2,000 feet during the runs and 6,000 feet on the cycle.
After the opening 100 miles following the completion of the first run leg and cycle, Rosemary was in fourth place in her category.
However, the hours of training runs on the steep hills around Allendale with Allen Valley Striders paid off as she took over USA rival Shelley Irwin.
Despite facing a spirited fightback from Shelley, Rosemary remained in third to earn the bronze medal in a final time of 11 hours, 13 minutes and 29 seconds.
It was an impressive time as she defeated several younger athletes and, with many others falling foul of the checkpoint timing rules which required participants to reach certain points in standard times, she was the oldest female finisher overall.
Such was the pedigree of the championships, the overall winner of the female race was Emma Pooley, the British Olympic cycling silver medallist, fresh from her appearance at Rio.
To celebrate her success, Rosemary immediately went on a cycling holiday!
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