The 'Two and a Half Men' actor picked up the Ultimate Choice Award at the fan-voted Teen Choice Awards ceremony in Los Angeles on Sunday, and took the opportunity to share some words of wisdom with his young supporters.
The 35-year-old hunk told the crowd: "The sexiest thing in the entire world is being really smart. And being thoughtful and being generous. Everything else is crap. I promise you.
"It's just crap that people try to sell to you to make you feel like less. So don't buy it. Be smart. Be thoughtful and be generous."
The laid-back star - who is dating Mila Kunis - advised the teenagers in the audience to seize every opportunity and not be afraid to create the life of their dreams.
Ashton added: "Everything around us that we call life was made up of people that are no smarter than you. And you can build your own things and you can build your own life that other people can live in.
"So build a life, don't live one, find your opportunities and always be sexy."
The funnyman was joined at the ceremony by a host of younger stars, including Miley Cyrus, One Direction and Demi Lovato.