AK,
I'll admit, I haven't been around nearly as much as I used to be, but each and every one of my friends here is very special to me.
I can totally relate to the situation you're in, as I continually wrestle with the same conundrum each renewal cycle. My COPD isn't going to get any better and it's getting harder and harder to hump gear.
Please know that you've been instrumental in the shaping of many careers, and at the same time, sent a bunch of 'hacks and quacks' packing back to the locker room. Remember that even if you do let the EMT-P license go, you've got a lot of friends here, and your knowledge of our craft will always be invaluable.
Besides, where would some of these 'wet behind the ears, know nothing, snot nosed EMT's be without 'Old Road Dogs' like us, whacking them with our canes once in a while?