Why Did God Give Us Side Stitches?A sharp, stabbing pain is your body’s protest against exercise.

From the show

Oh, god... really?

That sharp pain in your side when you run is a common, harmless complaint from your internal organs. Known as a side stitch, its exact cause is debated, but theories point to irritation of the abdominal lining or diaphragm spasms. The pain is essentially your body's built-in excuse to stop moving. So even a perfect design has flaws that keep you on the couch. It seems our own anatomy protests the very idea of going for a jog.