This short practice is a great tune-up for your major muscle groups.  Nothing too strenuous or radical, just strength and stretch of the "biggies".  This is a great practice for when you are short on time and also for beginner students. It's also helpful for teachers and more advanced students to touch up on the functions of the major muscle groups and how they affect movement. If your knees are sensitive, find alternatives during the first few minutes of talking…but make sure the quadriceps get a nice release and that you bend the knees as much as they safely go (without sharp / hot pain).