This move will increase shoulder, core, and arm strength and stability in your kickboxing practice. Lower yourself into a high plank position, activating your core and keeping your hips locked and level. Maintaining your plank form, lower from your hands onto your forearms one at a time. Raise up onto your hands back into a high plank and ground yourself before bringing one hand to touch the opposite shoulder. Bring your hand back to the ground, and switch sides, touching the opposite shoulder with the opposite hand. Focus on keeping your core strong and hips level, even as you complete each shoulder touch. Repeat!