In January I already got into a rickety side position. It was not so easy at that time! In spite of that I will try to increase the difficulty.
I start in the push-up position and rotate my left arm and the torso slowly and controlled upwards to the left until my right wrist, the shoulders and the fingertips of the left hand build one straight line. The left food is above the right one. Then I turn back in the starting position and continue on the other side. This is a very effective exercise for the body tense and the supporting strength.
Have a nice weekend.