He said it was beautiful to now hear te reo spoken on television.
Fifty years ago, 30,000 people signed Te Petihana Reo Māori, the document asking for active recognition of te reo Māori.
The petition, presented by Ngā Tamatoa member Hana Jackson on September 14, 1972, led to Te Wiki o te Reo Māori being established.
This year also marks 35 years since te reo became an official language of New Zealand, the other only official language being New Zealand Sign Language.
Neilson said some time around 1958 he was asked by elders to help with a claim to the Waitangi Tribunal for his iwi.
"When I asked my elders what they wanted and needed, they said they wanted to know why all of their papakāinga are now Crown land, and why our family can't go back to where our ancestors lived," Neilson said.
"There are places now we have to buy back the bones of where our ancestors lived."
He said it became an obsession, and still was an obsession.
"My ancestors and myself, and now my grandchildren, have been robbed of their heritage.
"There were over 100 villages on the Waitōtara Valley that were all chased off the land by colonisers doing 'ethnic cleansing'.
"I feel really sorry for my ancestors. In the late 1860s they had corn, peaches, sheep and cattle - but it was all either taken off them or burnt, and they were never allowed back."
He said talking about this history and making people aware of it was currently his reason for living.
"It's an ongoing issue, and I think that's why I'm 84 and I'm still alive. It keeps me going.
"It's a history more of the younger generation should know about. Our real history.
"Māori Language Week is wonderful, because when I was young we never saw anything like that."
Whanganui District Library's Pou Whiria Māori information librarian Jasmin Ratana said as te reo Māori became more normalised, every week would be Te Wiki o te Reo Māori.
"Then maybe we can use this week to remember those who 50 years ago sparked the revitalisation of te reo Māori for our future generations."
Ratana said the day Te Petihana Reo Māori was presented was a turning point for all New Zealanders.
"The important thing is that you give it a go. Everyone should get involved, have some fun, and be proud of our ability as Kiwis to make something happen."
UCOL Whanganui campus manager Bronwyn Paul said there was a clear demand for te reo programmes in the community.
"We have not run our popular te reo Māori programmes at UCOL Whanganui yet this year, as we search for tutors with the required level of te reo to teach the programmes," Paul said.
"But the beginner-level programme attracted around 100 learners in each of the previous three years."
Data released in July by Stats NZ showed almost one in four Māori New Zealanders now speak te reo as a first language, while 34 per cent of Māori New Zealanders can speak te reo fairly well.
Young New Zealanders are leading the way in te reo proficiency, with around 40 per cent of those aged 15-34 able to speak more than a few words or phrases.
The data showed 60 per cent of New Zealanders think te reo should be a core subject in primary schools.
Since 2018, the proportion of people able to speak more than a few words or phrases of te reo Māori rose from 24 per cent to 30 per cent. This follows a previous, smaller, rise between 2016 and 2018.
The proportion of people able to speak te reo Māori at least fairly well also increased, from 6.1 per cent in 2018 to 7.9 per cent in 2021.
"This is the first time a significant increase in this level of te reo Māori proficiency has been observed from GSS data," the Stats NZ website said.
For the total population, te reo Māori proficiency tended to decrease with age. People aged 15–24 and 25–34 years were the most likely age groups to be able to speak more than a few words or phrases, at 41 per cent and 43 per cent, respectively.
The largest improvement was seen for 25 to 34-year-olds, with the proportion able to speak more than a few words or phrases increasing from 27 per cent in 2018.
A large increase (from 6.3 per cent to 13 per cent) was also seen in the proportion of people in the 25–34 year age group who said they could speak te reo Māori at least fairly well, compared with a smaller increase (from 6.1 per cent to 7.9 per cent) for the total population.
The 2018 census showed 7.1 per cent of people in Whanganui speak te reo Māori.
Ratana said there were many ways people could engage with te reo Māori, including the website Te Rangaihi Reo, which had many suggestions and resources for ways to engage.
https://www.reomaori.co.nz
