My favorite exercise this week: The Bird-Dog

This exercise is simple & challenging. Start on your hands & knees on the floor (that move can be the toughest part). Extend 1 arm and the opposite leg, then switch to the other arm & leg for 10 repetitions. Remember to engage your abdominal muscle & exhale as you extend, inhale as you retract. When you are ready to add challenge, try it on the Bosu as seen below.

Once this get easy, add more challenge by extending the same side arm & leg, as seen below.