When you're 25 you begin to realize that you're not quite so invincible because you can't stay out with your friends and party all night and then get up and go to work like you used to.
At 32 you now know you're not invincible because your 7 year old son wants you to ride bikes with him when you get home from work and you tell him to go ride with that sweet little girl next door. but life is now your oyster even though you don't eat them but instead take the fam. to Applebees on weekends.
At 42 you definitely know you're not invincible because 7 body parts are telling you that you aren't including your eyes which now watch your son ride around in a car with the sweet little girl next door that now looks like a pop tart from the cover of US Magazine.
At 52 you know that you're not invincible but you act like it anyway because you're wife left and took the kids when she got sick and tired of you reacting really badly to her wild post menopausal mood swings.
At 64 you know you're not invincible because you can't remember any of the lyrics to "When I'm 64" from the Beatles, and you wander the parking lot at Wal-Mart because you've forgotten where you parked your car.
At 70 you wonder where it all went and invincibility begins to enter your mind but this time it's in the form of the afterlife so you start going back to church and asking God to give you everlasting life because you know that this one's in the can.
At 81 Invincibility is a moot point because just getting from your apartment to the dining hall is a major accomplishment, and you don't care if those whippersnapper 68 year old's to turn the volume all the way up on that ridiculous Jerry Springer because you can't hear it anyway.
Just remember...I am the Sax Player...