Thomas-
There are two basic types of AF: The kind that occurs randomly, maybe once a week, maybe once a year, and feels pretty much as Oldfrat described, like runaway heart; and the kind that's occurring all the time but you don't feel it. The second type is treated very successfully with shock (cardioversion) once you're stabilized. For the first you're pretty much stuck with Warfarin, Cumadin, etc to slow coagulation and prevent stroke. You may even get by with an aspirin a day instead, altho most cardio docs would pale to hear that.
Neither should have a major effect on your lifestyle. What CAN slow you down a lot, and what CAN trigger the AF, is sleep apnea, as someone mentioned. Sounds like that's what you have, and probably what caused your AF.
Have your doc get you lined up with a Sleep Clinic and get tested. The CPAP machines are just an abomination to use, but very effective if you're losing sleep and tiring easily.
(A FF board probably isn't the best place to get reliable medical advice, but you brought it up and we're all wannabe Dr Rosens.)