Well it depends, if by being "fit" you mean looking good for girls. And sometimes, genetics just works weird. You should do more cardio if you wanna lose the fat, but it might be your diet. There's lots of diets that work better for different people, some people have luck eating for their blood type, I'd love to try it, but I don't know my blood type. Some people have good luck with a high protein diet, some people have good luck with a high carb diet, you gotta figure out what diet suits you the most, what strategies/etc. Also, you need to get good sleep at night. If things are missing out of the equation, then things won't work.
Some people just have weird genetics, though. My friend knows someone that doesn't work out much at all, but can deadlift 500lbs at 200lbs bodyweight. This same person is like 10% bodyfat all over, except he has a belly somehow. Some of it is hormonal, ie, if you take a lot insulin, you'll get a belly from subcutaneous fat. Look at Ronnie Coleman for example, http://c249051.r51.cf1.rackcdn.com/7ccb ... 837be8.jpg. His gut is extreme and likely from HGH/insulin use (pro bodybuilders inject insulin to get more muscle growth.) In some cases, it's food allergies of sorts that cause it, I remember reading one nutritionist guy saying he worked with a pro bodybuilder who had a gut like that, and a switch from his carbs from oats to quiona got rid of the gut like instantly. Basically, there's lots and lots and lots of variables.
But, as Louie Simmons says "Powerlifting is not a good sport if you want a small waist."