Milestone or Millstone?

I am told that today is a milestone in my life. The occasion is my ninetieth birthday. I am glad to report that today was also uneventful. I was successful in keeping it low key and filled myself with the joy of a cholesterol laden dinner and the affection of my family. Life is indeed good when ninety years pass and one is still able to walk unassisted, drive an automobile and participate in a meaningful discussion with family. The challenge now is to keep this aging phenomenon from becoming a burden to family and a millstone for me. Fortunately I feel I'm up to the challenge (once I get this Zantac down)..