On Birthdays

 On My Twentieth:
 So much for my Longevity,
 (I have such a life to lead!)
 I've reached the age of Twenty.
 Let them judge me by my deeds! 

 On My Thirtieth:
 So much for my Longevity,
 (And I still have hair on my head.) 
 I've reached the age of Thirty.  
 Thank God I'm not Forty instead!

 On My Fortieth: 
 So much for my Longevity, 
 (And I still have hair on my chin!)
 I've reached the age of Forty. 
 Thank God I'm not Twenty again!