The 'Mirror, Mirror' actress feels like a "little girl dressing up" when she goes to red carpet events because she forgets how famous she is.
She said: "The Met Ball? Being invited to something like that? Incredible! I still think, Why am I on the list? I still feel like a little girl dressing up and getting to go to a pretty party."
Though Lily's father, musician Phil Collins, meant she grew up around famous people, she insists they never seems like anything out of the ordinary to her.
Speaking to the new edition of Lucky magazine, she said: "I never understood the word 'celebrity'. It was just part of my everyday."
The 24-year-old beauty has three tattoos, and says she has "always loved" body art, so never minds the pain it takes to have a design etched onto her skin.
She said: "I've always loved body art I remember being with my mom on Venice Beach when I was really young, and we walked by this guy on a Harley who was covered in tattoos.
"I was this little British girl, and I went up to him and said, 'Your tattoos are so pretty!' That was probably the last thing he wanted to hear...
"[As for the pain], look, women go through worse things. Waxing hurts more than tattoos. And tattoos are permanent, so if it takes a little pain to get there, that's OK."