"I decided there had to be a better place for Nana - and for other nanas too."
Mr O'Sullivan discussed his ideas with wife Rosie and they bought the Wanganui East Tennis Club to build a facility where everyone would have their own room.
Three years later the Whanganui village become the first in the country.
"That had a lot more land than we required for the main building so we built 14 units," said Mr O'Sullivan.
"As luck would have it, the land next door came up for sale so we built more."
Mr O'Sullivan said his wife came up with the name while they were sitting on the beach one evening.
"I thought of 'Sunset' but that didn't sound quite right and Rosie said 'what about Summerset?'."
Mr O'Sullivan said people are generally happy in summer and it is about wanting people to be happy with where they live.
The couple, who live in Kapiti, planned to attend the celebration in Whanganui next week but Mr O'Sullivan's 84 year-old mother is seriously ill.
"Mum has always been slim but she is down to 35 kilos now," said Mr O'Sullivan.
"It's hard for dad too - he's nearly 90."
"I feel pretty fortunate to have reached 62 and still have both my parents but it is a difficult time for anyone."
He says he feels proud of his first village and the fact that it still suits Whanganui residents after 20 years.
"Whanganui people like to get outdoors and get their feet in the sand.
"The single storey buildings and big grounds are very suitable whereas some of the villages in bigger cities are multi- storey with smaller grounds because that's what people want."
Summerset in the River City manager Shelley Walls said she loves her job at the village, where the well-established gardens include a children's playground and vegetable plots.
"Everything we do here incorporates John's original thinking that if you wouldn't want it for your grandmother, you wouldn't have it at Summerset."
Learn more about John O'Sullivan's story on Summer set retirement villages Facebook page.
