using kegels, you can orgasm without ejaculation, so there's no down time and you're ready to go again.  the endurance training i spoke of is mostly just having a lot of sex 

  for me it's just a mental thing, I'm not done until I want to be.  
sex may be about the journey and not the destination, but it's more fun when you don't need a 10 minute pitstop every 25 miles.