Sam and the tennis balls

It never ceases to amaze me that Sam always wants to play with her tennis balls.  Even immediately after returning home from her Chemo therapy treatment.  She keeps the tennis balls strategically located within the house.  When a request to go outside is heard, she promptly runs around the house to find the nearest tennis ball.  She absolutely loves to take them outside.  Wanting to go to the grass so I can throw them.  I have a standing order within my Amazon account for more Kong brand tennis balls.