I realize you are going to be 40 this year (however you look more like a great looking 20 year old), But what I am wondering is: Do you notice a difference in your endurance and strength from the 20 or so years ago? I wonder this because since you are so fit (or ripped like my husband says) and have been so fit since the beginning (I am sure), do the years make such a difference for someone like you? Thank you.