"This is exactly what I am talking about. Too often we stand back and laugh at others who are trying to achieve. It has to stop," he told the youngsters.
Earlier this year the now 40 year old broke the world record for the number of people (1711) doing squats at once, at Eden Park in February.
Letele, who is of Māori and Samoan descent, had a tough upbringing. His father Dave joined a prominent Auckland gang at just 13 and was president by the time he was 19.
As a youngster Letele had a highly promising league career cut short by a succession of broken bones. He turned his hand to boxing and travelled the world.
What followed was a battle with obesity, a messy break-up, and the collapse of his once successful supermarket chain.
Letele came through those setbacks, and it strengthened his resolve to help others.
Fale Pasifika Horowhenua organised what was the 8th Annual Pasifika Youth Jandal Jam, a Day Programme and show spectacular for Pasifika young people, and said they were honoured to have Letele attend.
There was a cultural performance at Levin Performing Arts centre that night.