The Duchess of Cambridge introduced an animated film created by the Anna Freud National Centre for Children and Families that focuses on that very subject.
"Hello, mental health is how we feel and think," she said. "Things that can't really be seen but that affect us every day, and talking about them can feel difficult."
"It helps us all to talk about our mental health: what to say and who to talk to when we have feelings that are too big to manage on our own," she said, "and how to listen and help if one of our friends is finding things difficult. Sometimes it's just a simple conversation that can make things better."