Here's a series of three exercises involving nothing but a piece of grass, carpet, or even the floor of your gondola.
I should clarify that these are not really stretching moves as much as isometric exercises.
They focus mostly on the lower back and upper legs.
"hip raised knee-squeezes"
This last move requires a little more coordination and concentration, but the results are worth taking the time.
Now get back on the floor and try "marching":