When I get up in the morning, I do some leg exercises before I start walking around. I think this started with a bout of plantar fasciitis a few years back.
First I alternately flex and extend my ankles 192 (64x3) times, with one ankle flexed when the other is extended. Next I write the alphabet forwards with both feet, then backwards (mirror-image) with both feet at the same time.
I've had problems with my hip flexors in some races. I had been trying to figure out an effective means of strengthening this area by laying on the ground and waving my legs around one way or another. I finally made the connection and now write the alphabet forwards then backwards with my legs (both at the same time). So far, I haven't made it all of the way through without having to take a break. But if this ever gets too easy, I'm going to start writing the Khmer alphabet.