How do I make my cheeks thinner?

I'm very petite but shaped nicely. I have a roundish kind of face shape and my cheeks look almost puffy in certain angles. So i was wondering how do i get my face to look thinner without plastic surgery like hilary duff, i have her face shape when she was younger now she her face is all thin. i want mine to look like hers and im 18 years old.. thank you!