Loss of oxygen (and damage) after 3-4 hours ...
After 3-4 hours of a continual erection, you'll deny the cells in your penis oxygen and cause damage. This will affect your ability to sustain an errection as you get older. You must be careful not to damage the cells in your penis by denying them oxygen.
Now it's not uncommon for men to have a full erection, not unload, it goes down some, and then rises back up after a period of time when stimulated again. Younger men are more sensitive to this than older or experienced men, and that factors into sustainment. As I'm now in my mid-'30s, I can sustain myself with greater ease without unloading. But I'll be honest, I can't keep it nearly as hard for as long as when I was in my early '20s.
When I was younger, errection without climax meant I was closer to climax, with a fuller load, when stimulation was applied again. If a woman stimulated me for several hours two days in a row, by the third day, I couldn't even last 30 seconds. It happened to me when I lost my intercourse virginity just after 18 -- my (fairly new and shortlived) girlfriend stupidly mounted me to prevent me from getting up and answering the phone (after our lovemaking had been interrupted two nights prior by phone calls that required me to come to work immediately) and was pissed at the result (hey, I tried to get her off of me and she didn't believe me!). It happened to me again when I first met my wife (to be) at 21 -- and she decided that it would be fun to tease me with her older sister in the room next door for the 3rd night in a row (her sister was constantly coming in to check on us -- yes, even though we were consenting adults).
Now as I'm older, my wife and I have far longer intercourse sessions. It's not uncommon for her to experience 15-30 minutes of intercourse at her pace and pleasure (my helmet works well against her G-spot) in between other moments of foreplay, before I finally climax (allow her to have at least 1, if not more). I used to be able to go more than 30 minutes in my late '20s (which seemed to be the best balance between youth and experience with her), but it's typically only sessions of 15-30 minutes of 2-3 hours total when we make love (we don't have kids yet, so we're still enjoying those long sessions).
Now I used to travel quite a bit (and still do on occasion, and it seems to be picking up again). I would sustain frequent errections as long as 18 days, until I saw my wife again. As I have aged, I'm able to hold off blasting immediately upon next stimulation -- something I wouldn't have been able to do in my late teens or early '20s (let alone I would have had a wet dream or two or even three over 18 days).
With that all said (and yes this is unrelated/off-topic) I think it's great for people to marry young! I've been enjoying my wife since I was 21 and she was 19. I've gotten to experience her physical (among other) changes for more than a dozen years, and she the same of myself. I've gone from having a tight, perky lover that used to constantly take me to the edge (and accidentally beyond it) to a maturing, softening partner who relishes in our mutual, sustained and complete estacy. And in another dozen years, I'm going to enjoy her ripe, middle aging figure and curves even more with my own, patient enjoyment.
How long can I sustain an erection? I hope for a lifetime -- and only one woman will take me there!
