Harrison (53), a Dunedin City Council transport officer, was diagnosed with MS three years ago but the disease has not stopped him from being active.
He demonstrated this when he came fifth in the 5km walk for athletes aged 50 to 54 in 46min 13sec.
''It was a great achievement for me to complete the race and to be part of a team,'' Harrison said .
''It was great to be able to do it. I didn't know what the time was when I finished. I just put one foot forward after another.
''It was a commitment for all of us and we trained as much as we could.''
It was the second time the Otago Multiple Sclerosis Society had entered patients in the event but the first time for Harrison.
''It was an exhilarating feeling to finish the race and know that I can do this,'' Harrison said.
It was not easy for him because ''my legs feel like lead weights. It was hard work but it was really great to do it.
''It was great to see everyone coming through and finishing. We support each other. That is the only reason we can do it.''
Harrison is the younger brother of Fr John Harrison, an elite runner in the Caversham Harrier Club in his younger days.
''I have run 10km and 12km races in the past,'' Harrison said.
There were eight people with MS and they were supported by family members, friends and Otago Multiple Sclerosis Society staff in a team of 20.
''Some found it quite challenging,'' the Otago Multiple Sclerosis Society manager Tania McGregor said.
''But the sense of being able to finish the race was awesome. Being part of a team environment and being out in the community is huge for them.''
The group trained for the games at their own pace and in their own time because fatigue is a common symptom of MS.
The common attitude for people with serious illness was to highlight what they cannot do.
''We work with our clients in a way to find out what they can do,'' field officer Jo Smith said.
''That positive attitude is huge for them. It is great to raise awareness and get people talking about MS because it is a hidden disease and you can't always tell who has it. We want people to talk about it.''
Two of the group impressed with their efforts. Nicki Mackle (32) finished first in the age 30 to 34 grade in 49min 36sec and Mel Hogue (35) was ninth in the 35 to 39 age group in 51min 36sec.
