"Now work those glutes, ladies!" the brunette with feathered curls shouted above the loud Michael Jackson single coming from the boombox in the corner. Dressed in a hot pink leotard and legwarmers, she led exercises on a foam mat atop the polished linoleum floor.

"You said this would be fun, Doctor!" Clara panted. Soft wisps of her brown hair stuck out of her neon green sweatband as she desperately attempted to keep up with the instructor's pace.

"What about filming an exercise video with Jane Fonda isn't fun?" the Doctor said, looking equally ridiculous in short, tight TARDIS-blue exercise shorts and a tank top, complete with clip-on bowtie. He grinned from ear to ear as he squatted in time to the beat. "One, two, up! One, two, down!"

"Keep smiling!" Jane yelled. "There you go, John!" she said to the Doctor. "Now everyone get on your mats! It's time for sit-ups!"

Clara sighed and collapsed in a heap on her mat. She could keep up with a dozen toddlers for hours, but she was never a much of a fan of organized exercise. The Doctor's "brilliant" idea was proving to be quite a challenge for her.

After two rounds of sit-ups, the camera stopped rolling for a water break. The exercisers walked off the set to find their gym bags. The Doctor playfully snapped a towel at Clara as she took a long swig from her multicoloured water bottle.

"Oi, you!" she exclaimed. He winked cheekily in response. Most of the fun of messing with Clara was her reaction, the Doctor thought.

"So, is this intended to replace our usual running?" Clara asked, cocking her head to the side.

The Doctor gave a sad, gentle smile, staring into the distance. "Oh, Clara," he said softly. "I'm always running. I never really stop."

Clara took another sip from her drink. She smiled. "This isn't as bad as I'm making it out to be. But you know, I get to pick the next place we go," she said.

"Oh, really, Ms. Oswald? Is that so?" the Doctor replied, raising his brow.

Clara nodded. "Yep. I'm the boss." She turned around and returned to her mat to stretch.

When the exercises began again, the Doctor really let himself loose. He shook, he pumped, and he wiggled in time to the music. When Jane asked for a shout, he gave the shout of an entire Sontaran squadron. His gangly limbs flopped all over the room, threatening to hit into the thin, twenty-something blonde with hair bigger than the lost moon of Poosh who was doing jumping jacks to his left. Despite his ridiculous appearance, he continued to smile, not knowing how silly he looked. Clara couldn't help but smile back at his obliviousness.

As the music reached a crescendo and the final chorus of "Thriller" played, the Doctor's moves became too much for even the forces of nature to handle. As he came down from a hop, he slipped on his right leg. He gasped, falling off to the side of his mat and tumbling into Clara. The crash was so thunderous that it caused the boombox to skip, leaving the room with an awkward silence and a lanky man on the ground. He laughed nervously and looked up at Clara.

"Well, Clara, we'd better be going now," he whispered. The video take was ruined and the whole room glared at them. Clara bit the insides of her cheeks raw trying to conceal her laughter as they shamefully gathered their belongings in a hurry, the Doctor muttering curses about gravity and Sir Isaac Newton all the way to the door.