Need some professional help?

The thing with the sagging skin is that fat is not area specific. That means you can't just lose fat in one part of your body. My advice to you is to eat right and find a gym and lift your entire body and do various ab workouts every other day until failure. Remember that when you workout, you need to keep your heart rate up and make sure you are doing enough to sweat. it will still take some time and it will not be easy, but over time, you will be healthier and will get the six pack you want.