The day involved a mix of rugby drills and life-skill sessions, with the two players sharing their experiences with the aspiring young players.
As Teen Rugby Ambassador for New Zealand Rugby Union, Williams said he welcomed the opportunity to "spread a positive message that these kids can do anything with their lives.
"If you make a positive change in your life or make positive decisions, it doesn't cost much," he said.
Williams said he enjoyed his involvement with programmes like E Tu Rangatahi, partly because they gave him a break from his everyday media duties, which could sometimes be "a bit of a bore".
Bay of Plenty and Maori All Black hooker Joe Royal was also grateful for the chance to spend the day with students. "It's quite a privilege to come here and talk to kids and help out."
The Rotorua-born player described the kind of wisdom he and Williams had been passing on to students.
"It's how we have come to be in the position that we are in and the journey that we have taken to get here. There's quite a few superstars around with good skills ... [and] we told them, it doesn't matter where you come from."
For Levi Whata, 18, the day had been a chance to develop his leadership skills.
A cultural and social prefect at Tarawera High School, Levi said the surprise visit from the players was a great boost for the students at the school, and for the whole town. "It has been amazing. A life- changing experience pretty much."