"I was really excited to take on a princess knowing that we wanted to maker her kind of feel stronger and more of a strong female lead character," says James

Lily James snagged the role of a lifetime playing the title character in Disney’s new live-action reboot of Cinderella, and she knows it.

“I loved all the princess films and I grew up with them, and I think it’s really cool how they’ve changed over the years – how the princesses have become more positive role models right up until Frozen,” says James, 25.

“So I was really excited to take on a princess knowing that we wanted to make her kind of feel stronger and more of a strong female lead characters,” she adds.

The actress, best known as Lady Rose MacClare in Downton Abbey, opens up to PEOPLE in the latest issue. Here are five things you need to know about this rising star.

1. Performing is in her blood.
“I don’t have an exact moment when I decided I wanted to be an actress – it kind of was just really a part of my growing up. My dad [Jamie Thomson] had acted at one point in his life and he played the guitar, and I was always singing. I love to sing. Music was a really, really big part of my growing up. My dad would take me to see a ballet every year for my birthday from when I was tiny, and my grandma [Helen Horton] was an actress. I just think that in my house there was always that feel of storytelling.”

2. Turning into a princess takes some work.
“My skirt was so big I was like this beached whale, and no one could get near. [Helena Bonham Carter and I] both had our own tents, and we were screaming for the other, and it was hard to walk and sit down, so it was a really hard skirt to sort of navigate.”

3. Her favorite Disney princess is
“Belle from Beauty and the Beast. I think she’s my favorite because as a kid I had long brown hair, and I think you always side with the princess that you think maybe you could look like. It’s a bit like the Spice Girls – I was always Sporty Spice.”

4. Downton Abbey is a dream job.
Downton was a mad experience. I loved the show, and I’ve always wanted to do period drama. Honestly, the cast gets along really well and we all know each other. We’re all really close. Michelle [Dockery] and Laura [Carmichael] just texted me on Sunday and were like, ‘We see you and you’re a princess!’ They’re so sweet, so I’m really looking forward to going back.”

5. She’s found her own Prince Charming in her actor boyfriend Matt Smith.
“I think I feel most like a princess when I’m sort of bursting with happiness and love, so whether that would be like with my boyfriend or my family or at a really fun party – just when you’re full of life.”

For more on the stars of Cinderella, pick up this week’s issue of PEOPLE, on stands now