No one wakes up one morning and casually decides to go run a marathon.   “See you later babe.” “Where you off to?” “Oh, just run a marathon. I’ll be back in time for lunch. See you later.” “Ok bye babe. Have fun.” “Love you.” “Love you.”   Does this sound like a completely and utterly ridiculous conversation, not to mention, extremely unlikely?   Yes. Yes, it does. And you know why? Because in the realm of things that can actually happen, this, friends, is probably not one of them.   You can most certainly wake up one morning and decide that you want to start training to run a…