She used her powers of persuasion

"But there is nothing wrong with it." Dr. Valentine began using her powers of persuasion to convince Joan once again. "Didn't it feel good to jerk it off?"

Joan had to admit it felt good. She even had a minute-long orgasm from jerking off. But that wasn't what she wanted. Instead of a huge cock on herself she wanted one in herself. "I'll never again get a man to fuck me with this things!"

"But that isn't true." Dr. Valentine assured. "Just look at yourself." She stepped beside Joan and turned her towards the mirror, which Stacy was still cleaning with a towel. "You have become such a gorgeous woman. Endless legs, wide hips with a big ass, big breasts nearly popping out of a sexy dress and lips made for kissing and cock-sucking. What kind of man wouldn't be attracted to such a woman?" Joan looked at her reflection again and saw that Dr. Valentine was right. She really looked gorgeous, like a wet dream. "What kind of man would reject a fuck with a cougar like you? Neither young nor old could resist you." Joan realized she now had the power. She did look totally different, she did look like a mature woman around 30 years older than she really was. But the look of a cougar-Milf had its own charms. And what man would resist sex with such a hot Milf?

"Perhaps you are right." Joan said smiling at her reflection. "What man could resist me?"