They say, (the ever present communal memory), that our body replaces all of its cells, except brain, every seven years. So every seven years, you have a new you. That seven thing is also present in common thought with the "seven year itch" concept.
So, I'm 49. That's seven sevens. Here I have been, waiting for the great 50, which much of our society thinks of as an achievement and celebrates wholeheartedly (here in the Ozarks I might get to go beyond "young pup" stage when I hit 50) and I almost missed that I was this great and wonderful age of 49!