Healthy Living will Kill You

I have never been enamoured with the thought of exercise. Exhortations to get fit and be healthy have largely passed me by. I think this has something to do with the people who deliver these messages. They never look happy.
Oh yes their bodies may be honed and muscled, they may be able to run marathons and leap over a row of prostrate fatties in a single bound but they always look like they are grimacing.
No matter what they do it never seems to be enough,once we get fit they are working to stay fit or trying to reach the next level of fitness. It is a never ending grind of exercise and more exercise for no particular reason except to attain some ill defined and seemingly unattainable goal.
Where is the fun? Where is the contentment? Where is the moment when you pat yourself on the back and say well done?
I keep asking in the hopes that one day someone will explain it all to me.