Longer

Snort a couple of lines of methamphetamine a few hours before sex. I could fuck for two hours straight on that shit without getting a nut. Just don't do it every day, because it is a bad mother fucker and will literally kick you right into the depths of Hell if/when you get addicted.

Smack your dick a lot

Two popsicles sticks and some duct tape

Wine.

L-arginine. 5 capsules in the morning, 5 in the evening. Cheap too. Makes me hard as a rock.

I have also tried L-Argenine, and noticed the same result

Desensitizing creme. It's right next to the condoms at the drug store.

Black licorice has something in it that makes your dick hard, and it always worked for me. Sometimes cock rings can do the trick, but those can be expensive, so go with a nice snug girls hair scrunchie. Switching positions regularly helps, with your cum position (doggie style for me) always last.

People with high blood pressure should avoid Liquorice as it can ramp up your bp

What a way to go, shooting a big load of cum as your heart goes out and you die

Check out Horny Goat Weed extract - I know you said non-medicinal, but this is over the counter and it definitely boosts your libido. Not sure if it affects stamina though!