At the risk of a lot of wise cracks (c'mon I'm curious about everything
, why not sex?) I'll give my 2 cents.
First of all it's important to understand the "problem". Except in severe cases the bottom line is that the real problem is simply ejaculating before your partner climaxes.
This isn't just a time factor in most cases, as the female orgasm isn't just about time but also greater complexity and except in the most extreme cases "lasting longer" shouldn't be the goal as much as having more control and being able to better work with your partner.
If you are on the extreme end (we are talking seconds, not minutes here) then I don't have a lot of advice (but I think this may change with age) but here is what I think works insofar as control goes (in order of efficiency):
In a gross simplification, the faster you move the more quickly you ejaculate. So controling pace is a big part and in its extreme is represented by pausing. But there's a lot more to it than that. Holding a steady pace and using the right pace for your partner are the most important things. The female is more sensitive to pace when it comes to being able to reach orgasm so you need to find a pace that both stimulates her while not over stimulating you.
This one is the most powerful thing you can do to control your ejaculation.
For starters, as you get closer to orgasm, your breathing quickens and shortens....knowing this, you can then take deeper and longer breaths
I'd also like to add that holding your breath (which is an instinct when reaching climax) focuses the sensation.
Controlling your breathing (slow and deep) is key to controlling your sensations (e.g. it's a big part of the Lamaze Technique's method of controlling pain).
Controlling your breathing is a big part of being able to control what you feel, and with more control well, you get it.
Some positions will cause faster ejaculation than others. For example, "doggy style" is a pretty common one to make it go quickly for the guy and more slowly for the girl.
Each person is different, however, and you need to find what works for you. Sometimes not controlling the movement (e.g. girl on top) will give you more control of your feelings, sometimes it won't.
Find out what are good positions for you and your partner for different goals (her pleasure, your climax etc). Each position has different positives and negatives and understanding them will help you and your partner control your experience.
Another option is "clenching". The same action you make to "hold it" when you need to urinate badly has a similar, but different, effect on ejaculation.
the point of no return puts off the point of no return a bit (you may initially only get a few extra seconds this way). However clenching also forces more blood into the penis, making it harder and more sensitive. So clenching without pausing may cause an immediate ejaculation in some. Having more control over this takes a bit of practice (practicing alone will speed the learning curve).
Other things that control your arousal levels are your energy levels (when you are tired you have lower arousal levels), refraction period (how recently you ejaculated and how long it takes your body to reach normal arousal levels afterwards), your fitness, and substance use (drugs, smoking alcohol).
But most of all, and I really mean this, relax! Don't over think it. Don't worry about it. I think pressure is a big cause of premature ejaculation.
P.S. The testicles retract to the body close to orgasm. Some people report good results from pulling the scrotum away from the body gently (and there are various "rings" and things for that as well). There are also penis rings that restrict the penis blood flow.
I don't think those are as useful (and the penis ring can be dangerous) as they are unnatural and intrusive (and I imagine are awkward) and really think you can do it all with a better understanding of what positions do what, a better understanding of your partner and the basic pace/breathing/clenching controls and you'll be fine.