|Robert Pattinson and Reese Witherspoon in "Water for Elephants"|
She told MTV News: "I've never experienced what he has -- going to premieres and there's just millions of people waiting for him to touch them. I think it must be strange, but I don't even know how to process what he deals with and Kristen [Stewart] deals with. I don't know. [He's]a really cool guy."
Reese also revealed that fame hasn't changed 25-year-old Robert and says he is "appreciative" of his success.
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She added: "I would say [he is] the hardest-working person I've ever worked with, honestly. [He's] professional, hard-working, so appreciative, more grateful than I've ever seen anyone for where he is in life."
Robert and Reese are so close that the British actor reportedly sent the 35-year-old star some glow-in-the-dark exercise clothes after she was hit by a car while out jogging last year to ensure she doesn't suffer the same fate again.
The gift parcel from Robert contained reflective vests, wrist bands, tennis shoes and a hat - all of which were designed by Stella McCartney - and was sent to the actress' house along with a note wishing her a speedy recovery.
A source said: "Reese was very touched by Rob's gesture.
"She intends to keep running and the gear will come in very handy when it's dark outside."