Another one of the super quotes from Jack Kornfield:  A Path with Heart:  ‘the mind is like a puppy’.

When you are training a puppy it runs away many times and you gently bring it back to the training – this is like the brain.  Many people still expect their mind to be calm like a lake after a few meditation sessions which then can dishearten them and makes it more likely that they will give up.  Remember this if you get frustrated in meditation.  Unfortunately, mine is also like a magpie – attracted by shiny things – not quite as cute!