She's helping him with endurance training.

“The endurance training, silly!” said Karen.

Mr. Sawyer looked slightly confused, but tried to cover it up. “Sure, endurance training. Um, I forget, why did we want to keep that a secret from my wife?”

Karen smiled and winked at the older man. “You said you wanted to surprise her with how much you've improved.”

“Oh, right. Yeah, sure. Well, I just finished my strength training. I guess you could come over right now.”

“Great!” Karen walked around the fence. Mr. Sawyer started to head back to his exercise equipment in his back yard, but when he saw the redhead moving towards his front door, he hurried to get there first and open it for her.

Once inside, Karen continued to take advantage of his confusion. “Just sit in that chair, like you always do. I'll set up.”

Mr. Sawyer sat down, his confusion turning to nervousness. Being alone inside his house with his sexy teenage neighbor felt scandalous. Plus, in his hurry to get inside, he'd left his shirt in the yard, so he was alone with her and half naked. He reassured himself that he'd done if before without getting in trouble, so it must be fine.

Karen finished examining his sound system and selected a song. As the slow, sexy music started, she walked in front of the older man and started to dance. Her movements were slow and seductive, gracefully twisting her lush hips and pushing out her ample chest.

“Uh... Is this... is this really the best cardio workout?”

Karen laughed and ran a finger over his cheek. “Don't be silly. This isn't training for cardio endurance, it's for sexual endurance. Sexual endurance training is a common exercise that's vital for a healthy marriage. You told me you really wanted me to help you so that you could continue satisfying your wife. I think it's really sweet that you're willing to do this for her so often.”

“Yes, of course,” said Mr. Sawyer, nervous, but more accepting now. “It's all for my wife. To make my marriage stronger.”

“That's right!” Karen crossed her hands over her head and continued to dance in a sultry way. She turned around and rolled her hips so her perfect ass gyrated right in front of her muscular, older neighbor. When she turned around, she was pleased to see a full tent in his workout shorts.

“I think it's time for the next stage of the training,” said the sexy redhead.