The fastest ever tennis serve was recorded at

   163.4 mph
   Mach 1 – resulting in a sonic boom
   155.6 mph

Your lungs are

   Equal in size
   The right lung is bigger than the left
   The left lung is bigger than the right

Exercising your heart

   Makes you more romantic
   Helps create new brain cells
   Makes you tired

You will find the hammer and anvil

   In the tools section of the Argos catalogue
   In your foot
   In your ear

The human body emits light

   I’ll tell you after dark