I have always had a very high sex drive, even before I knew just what that meant. I was already crushing on boys (and some girls) at 3 and 4 yrs old and not just my own age, but grown men, lol.
The only times my sex drive has diminished a little has been due to pain/illness or medication as ShySEXXaddict mentioned. But, even when I tried antidepressants for my migraines, I still had a drive, I was just unable to orgasm! Good thing it didn't help my migraines so I could get off the medicine. I can't believe what a raw deal it is for a depressed person to feel better, want sex and then find out the pill helping them, is actually stopping them from one of reasons you want to live!
When I'm extremely nauseated or in extreme pain, I lose my sex drive, but as soon as the illness or the pain subsides enough to not be all consuming, the urge just comes right back! Even if I don't masturbate for a little while, my body takes care of it while I'm asleep - I will have orgasms while sleeping and since I'm such a light sleeper, I almost always wake up during it. (If I don't awaken during, I can tell when I do get up because of the 'evidence' shall we say.)