The whole thing with 'Rock Your Body' is that at first you think "hmm, this isn't as jaw-droppingly good as his last two singles, there are better tracks on the album than this", and then by the 25th time you hear it you realise that it is permanently engraved in your brain, utterly effortless and gliding and fun like being in the park on a sunny day. Justin is my avatar. If you believe you can dance that well, one day you will too, young 'un.