I don't think motivation will be a problem, I read somewhere that Robbie had already met Rafael Benitez during a celebration in a pub some time back and the entire pub of fans started chanting "Sign Robbie, Sign Robbie" and sang You'll Never Walk Alone all night long. I'd be amazed if he found motivation a problem, with fans like that.
That and the fact that he's a Kop favourite, of course. Never been a fan of Crouch, personally.