The former Lyreco and RAF worker said it felt like being surrounded by a football crowd as he finished the milestone run on Saturday morning.
For six and a half years, Jim has been an active part of Telford parkrun, spending every Saturday morning running through the town's park and helping to inspire the hundreds of people who run alongside him.
Local legend Jim Hussey, former @RoyalAirForce PTI, completed his 300th @telfordparkrun today at 81 years young, he's missed just 14. Kindest gentleman you could ever wish to meet, an inspiration to us all! How's this for a finish line atmosphere? @parkrunUK @paulsintonhewit pic.twitter.com/vxEGE9n6NB— Telford parkrun (@telfordparkrun) September 28, 2019
It was a return to an old passion. Jim had been a talented runner in his youth, running five-minute miles and marathons, but work meant he put it aside for several years.
And although he says age has slowed him down, he is still managing to teach his young fellow runners a thing or two.
"People say they hope they can do what I can do when they're my age," Jim said. "What I could do and what I can do now is completely different – there are no comparisons. But I try to go out and do anything from four to seven miles every day."
Hundreds of people gathered at the finish line to congratulate Jim, from Sutton Hill, on his achievement. The crowd clapped and cheered as he came into view.
Jim, who had eight children, about 25 grandchildren and about 10 great-grandchildren, was the man of the hour, being pulled in every direction for pictures and conversation.
The volume of participants is a far cry from what was expected when the group was first formed.
"It's a friendly group," Jim said. "It is purely for enjoyment.
"When it was first mooted that we wanted to do a parkrun, the powers that be asked us how many we expected. We said if we could get 150 to 200, we would be happy. Now it's very rare we get less than 400. Our record stands at 699.
"Dozens of people came up to me on Saturday and wanted selfies and things like that. I have inspired them and encouraged them over the six odd years I've been doing the parkrun. That gives me as much pleasure as when I was younger and running seriously."
Inspiring others is one of the things Jim enjoys most about his time at Telford parkrun.
"The park run isn't a competition," he said. "It's just a friendly social run for anybody from tots up to my age and everything in between. All shapes, all sizes. It has inspired so many people to come out and run.
"The idea is to get people out there, to get them fitter and to make them feel better in themselves, mentally and physically. There's the camaraderie as well. People from other park runs say they think this is one of the best in the country.
"I'd encourage people to come along. We are there to encourage and inspire. It doesn't matter what pace hey can do, as long as they are persistent. We will never leave anyone behind."
That supportive attitude has led to more than a few success stories, Jim said.
"I've seen vast improvements with people who have come to join us," he said. " They could barely run, didn't have any self confidence. We have seen vast improvements.
"I'll encourage everybody, and hopefully I inspire everybody. I appreciate there are people who just think they can't have an 82-year-old bloke beat them. If they'd done what I'd done in the past, they'd know it's no disgrace to be beaten."