Go to the sauna.

"Hey mom," you start, "I think you've worked out enough, you should try the sauna. It's very relaxing."

Kathy gives you a funny look, she's confused by this act of kindness, she assumed you would make her do something embarrassing. "That sounds great Jim." Your mom heads to the women's locker room, just as she reaches the door you tap her shoulder. She turns around. "Sorry, I forgot to mention that you will be using the men's sauna." You say with a devilish smile. Kathy enters the men's locker room.