Most of us are so accustomed to hunching over our desks, computers or handheld devices that we don’t even know what good posture is. “Look in the mirror. If your palms face your thighs with the thumbs pointing ahead, that’s good posture,” says Brill. “But if your palms face backwards, you’re probably slouching.” To see what your posture is supposed to look like, pull your head back and your shoulders down and back. It will feel as if you’re sticking out your chest if you’re standing up correctly.