I Can't Believe I'm a fitness fanatic

I distinctly remember giving running a go when I was in my early 20's. My effort comprised a brief explosion of effort which took me 5 minutes up a hill near my student flat in Sunderland and then ended in me collapsing in a breathless, crumpled bundle on the pavement. This episode of youthful effort came back to me today upon passing my 19 year old student friend Ben at the local gym where he was admirably attempting to get fit through weightlifting. The worthy image of him pushing at a reluctant bar on a bench press was juxtaposed later in the day when I visited his facebook site to see a gallery of photos which all featured him drinking and, in no uncertain terms, 'partying'. Ah the memories came flooding back. So what has now changed my attitude so drastically? Is it wisdom, the sudden awareness of mortality, lack of cash or time to go partying or just one last desperate attempt to 'get fit' before I pass the point of no return? Who knows, but what is for sure...The 19 year old self which never seems to have left me is looking at me now in wonderment and disbelief as I run miles on road and treadmill, do squats until I can't walk and abstain from alcohol and overload on protein with my sights set on an unimaginable goal...and I whisper to myself again...'I can't believe I'm going to run a marathon!'.