Exercise: The Invisible chair
Situation: On the phone
The Invisible chair is a killer leg exercise for when you are on the phone. Find an open wall to sit against. Try to get as close to sitting in a 90° angle as possible and keep sitting for as long as you can. It might also be a good idea to split this workout into a couple of sets because otherwise the person you are on the phone with might start to wonder why you sound funny.