Why, you insolent pup! If you'll just come over here, I'll give you what for! Too old at 39!
I'm 54, and the youngest pilot (of 4) at my EMS base, and only slightly above the average for our program (18 pilots).
EMS'ers tend to be a little older, but we have the occasional pilot in their 30's.
NO, you're not too old. Being young, foolish, foot-loose and fancy-free are the rules in a nomadic profession, and you'd have time to do wild goose chases, if you were starting at 19 or so....
Being settled, mature and purposeful is always beneficial, no matter the extent of your years on this earth.