Hey, I like to stay fit. Do you exercise?
No i don't In fact i tried to wash my car this morning and had to stop because i was so out of breath.  If physical fitness is the state of well being, i am just the opposite.
Interesting. That's too bad. Do you know much about fitness? I haven't been doing it long, and would love to learn more. 
There's not much to know: eat well, get a lot of exercise  and sleep.
Do you know when people started to be conscious of staying fit? I know there were Roman Gladiators.   
The term physical fitness is a relatively modern term: Before 1700, fitness was considered to be the ability to carry out daily tasks.  I do not even meet this definition.