I am currently between 8 - 9% body fat.
I've been there before (in 2006), but it was a huge amount of cardio and resistance exercise and very restrictive diet, which included: tirelessly counting calories, eating 6 small meals per day (which left me feeling hungry), constant balancing of macro nutrients (am I eating the right carb/protein/fat ratios?), absolute compliance to the meal plan (my ¼ cup of oatmeal with protein powder and ½ an apple for breakfast, etc, etc) , tons of supplements, and almost no cheating. This time I did it effortlessly.
But more importantly - I haven't fallen off the wagon since reaching that body fat % 3-4 weeks ago, and I have no urge to binge. In 2006 I was below 9% for about 5 days before I went off on a 3 month sugar binge (gaining back over 20 lbs). For me the sustainability of this life style is the true success.
"You have succeeded in life when all you really want is only what you really need." ~ Vernon Howard