Plank with shoulder taps

Get on your hands and knees, with your hands positioned a little wider than shoulder-width apart. Your shoulders, elbows and wrists should be in a straight line.
Extend your feet backwards and straighten your body. Spread your legs slightly wider than shoulder width.
Contract your abs, glutes, quads to align your body so that your head, shoulders, spine, glutes, ankles are in a straight line. Your neck should be neutral.

Tap your shoulder with your opposite hand, then perform with the opposite side.

Tapping your left and right shoulder counts as one repetition.
Perform for the recommended number of repetitions.