If you look at this clip of Penny settling down on her beloved old green mat, you'll understand why it has been hidden in the cupboard for the eight weeks since her surgery on her knee.
It had been brought out twice over the last few weeks and each time Penny terrified me by her enthusiasm for it. To her dismay it was snatched away each time and put on the shelf.
But I reckon, after eight weeks, it's time to let her enjoy it. That leg is certainly getting plenty of Passive Range of Movement exercise.
Here's an article I've just come across, by Greg Harasen, discussing the benefits of postoperative physical therapy.