Start in standing position. Lean down, keeping legs straight (will help stretch out hamstrings) and place hands on ground, getting in a pike position. Walk your hands out to reach a plank/push-up position.
In variant 1 do a push-up and then return to standing position in same manner as you reached push-up position, walking your hands back to your feet and standing up. In variant 2, perform a Tiger push-up, and return to standing position. In variant 3, instead of walking hands back to feet, walk your feet to meet your hands and then stand up.