I will admit, as a young child, the first few summers at camp weren't easy. I was constantly homesick, always thinking about what my parents were up to back at home. I would write letters daily ...

"The camp called, they felt really bad. They were like, 'Don't worry, she's happy,' " Jenna Bush Hager tells PEOPLE about daughter Mila, 8, writing a homesick letter from summer camp in Texas ...