Consider the following:
For all you tough guys/gals out there that think you don't need a PFD. Take a dry change of clothes with you the next time you go out, then... when you're in water over your head (7-10'), jump in fully clothed (long pants, shoes, and shirt) and see how far you can swim... Then when you get tired of swimming (which won't be long with all those clothes on), see how long you can tread water! Then when you're pretty tired of that, try to climb back into the boat!
IF you can get your ass back into the boat without help... I'm sure you will have a different outlook on wearing your PFD!!!
Try it, you aint as young as you used to be!