Funnily enough I've been the other way round - when I started having sex in mid-30s (don't laugh, please!) I was only semipotent to start with, then something just clicked and no trouble since - though I can't pop more than once per hour. My biggest worry is cumming in the first 5 mins from oral so I have to pace myself so I can last 15! ;-) But I'll easily go a month without any sexual activity in between - or until I found a girl up the road who does 30 mins for £40 that is.
There's a good book called "The Tao of health, sex and longevity" by Daniel Someone that may have all the answers to these problems, it's got a whole section on sex, how to do it, ejaculation control etc, there might be something there that can help? It talks about Chinese sages in bygone centuries who lived to incredible ages through their practices (200 years + in one case), they would live up in the hills growing herbs, when they brought then to market they would hire a couple of WGs with the proceeds, bring each to orgasm a couple of times - but without allowing themselves to cum as that would have depleted their internal energies! ;-)