You start to feel a tingling all over your body, and the werewolf notices your reaction. "That'll be the changes starting." he says.
Fur starts growing all over your body, and your face seems to elongate as you grow canines and a muzzle. Your cheeks and ears change and grow too. Your hands are larger and hairy, with harder pads on your palms and fingertips, and claws for nails. Your shoes grow tight and burst open due to your new big wolf feet. Your shirt also looks like it's stretched to breaking point too because of your broader, more muscular chest.
"Looks like the change was a sucess, kid." says the werewolf.
"Wasn't as painful as it was in the movies." you tell him
"I'll leave you to get on with experiencing your new body, but if you need me, just howl." and with that he runs off through the woods, leaving you to examine your new werewolf form