Prince Harry said he believes young people hold "the solutions to some of the world's biggest problems" as he spoke at the inaugural summit of Barack Obama's foundation in Chicago.
The Prince, who attended the event a year on from when news of his relationship with American actress Meghan Markle hit the headlines, said the younger generation had "turned me into an optimist", as he talked about meeting young people across the world.
He said they gave him "all of my passion and inspiration", adding: "The younger generation... are the best connected, the most passionate I think we've ever had.
"So what we need to do is we need to create a platform so they can be heard, because they have the solutions to the some of the world's biggest problems."
The 33-year-old spoke openly about how his late mother Princess Diana had inspired him to use his role to help others, and talked of the work of the Royal Foundation, which he set up alongside his brother Prince William in 2009.
He was joined at the summit by Chantelle Stefanovic, a project coordinator at the Full Effect programme in Nottingham, which is supported by the foundation.
The project, which Harry has visited several times to see its work in action, aims to inspire youngsters away from youth violence and gang-related activities.
Ms Stefanovic, who grew up in the city's suburb of St Ann's, told the summit of her difficult upbringing surrounded by deprivation and crime.
She said: "When you are... growing up knowing that your mum is missing her dinner to feed you, all you want to do is help, and you help by any means necessary. The solution for me when I was younger was to help in a way that was quite negative."
She eventually turned her life around, becoming involved in community projects, and now uses her experiences to help other young people create a better life for themselves.
She was praised by the Prince for the effect she has had on the people in her community.
He said: "She's making sure they have better choices and that they don't end up making bad choices.
"Before she was around, primary school kids of the age of seven or eight years old were being used by their older brothers to move knifes, to move drugs around.
"She herself at a young age was used in that sense as well. She's using her experiences to make sure other young kids don't have to go what she went through."
The Prince also spoke of the Heads Together mental health campaign, which is led by The Royal Foundation in partnership with eight mental health charities.
He said he believed the UK "was ready for that discussion", adding: "Everybody started to realise 'not only do I know people who might have suffered, I might have suffered as well'.
"Then you realise more people might have suffered a mental health issue than haven't."
Earlier in the day, Prince Harry and Michelle Obama had surprised students at Hyde Park Academy high school, in the south of Chicago.
He talked to the students about how young people can use their voices to change the world.