Start off in a straight arm plank position. Generate a full body tension, squeeze your glutes and hold this position.
Lift off your weight to one arm, touch your shoulder with other arm and reverse the movement by putting your arm back on the ground. Continue by moving your weight to other side and do the same movement with opposite arm.
Continue doing this movement by touching your hips, knees and feet with both arms. This is one repetition.
Taking your arms closer or putting your legs wider will make this exercise easier.