Young fellas, a word of warning.  Some stats from my life.

When I was 45 years old I was 6 foot tall, a lean 185 pounds, and my cock would get instantly hard and top out at a throbbing 7 1/2 inches with plenty of girth, or so the ladies said.

 I am now 69 years old, barely measure 5 foot 11 inches and  carry 15 extra pounds, mostly as love handles.  If that wasn't bad enough, my cock now tops out at about 6 inches max!  It still works without any medication, thank God, and I haven't noticed much reduction in girth, but I kinda miss, maybe even long for that extra inch and a half.  Where'd it go?

I'm stroking my cock right now.  There is still plenty there and I still adore it, and after 48 years of marriage I still find it magical sliding my cock into my wife's wet, hairy, still pretty tight pussy.  Generally I lick and suck her gash for a while, and when she gets close, I'll close the deal with a vibrator in and out of her cunt with long rests on her clit.  She almost always cums, and her orgasms are massive toe curlers that last 20 to 30 seconds, shaking and quivering and having spasms the whole time.  I envy her those climaxes! When she's done I decide what position I want her in, usually one where I can watch her ass shake and jiggle while I'm pounding that sweet spot.  After  awhile I'll feel the cum building up and may slow down to keep it going for a while, but usually I just let the dam burst.  My cock goes pfft, pfft, shoots out way less cum than it used to,(I know that because back in the day when I'd cum on her big titties,  I could pretty much fully glaze both those 34D cupcakes.  Now, there's barely enough to cover even one nipple), and it's over in about 2 seconds.  Then I start thinking about next week's session.  

There it is boys.  Take care of yourselves and find a good woman and you can fuck into your 70s, even if your cock is not the sap spewing tree trunk of your youth.