Sarah Jane had awoken in the morning to feel...well, she felt a whole lot better than she had in years and years. And by that, she would honestly say it had been thirty years since she had felt this spry. Twenty-three, when she and the Doctor were still running about, having just dropped off Harry.
She'd sat up, all her clothes fitting a bit loosely and when she peered down, everything was a bit firmer...and her hair was thicker and after a quick look at her feet, she saw K-9 hovering. "Mistress!" he announced eagerly. "You appear to be young!"
"How young?" she asked critically.
A quick scan later, K-9 chirped loudly. "Twenty-two!"
Sarah couldn't even take it. She just clasped her hands over her mouth and laughed giddily, throwing open the door and running down the stairs, intending to find the first person she knew to cry about how wonderful this was.