When attempting to flatten your stomach, always look at your nutrition to be sure you're not consuming more calories than you are burning. Also, find an exercise that you enjoy and you will see results.
If you're looking to flatten your stomach or improve any body part, there are two things you need to do. First of all, look at nutrition. Make sure you're not eating more calories then you're expending and you've got a nice balance of protein, carbs and fat.
Of carbohydrates, try to have a low glycemic index. That means slow releasing carbs. It really does make a difference.
Secondly, training. Now, there are lots of different types of training. There's cardio training, circuit training, resistance training.
It can become quite overwhelming. One relatively new idea is kettle bells. Kettle bells are actually really, really old but they've become very, very popular among celebrity trainers and gyms in the last 10 years.
A kettle bell is just a weight with a handle on it. There are lots of really fun swinging exercises we can do which burn fat and also tone up at the same time. I'm going to show you the fundamental cattle bell exercise, which is called the cattle bell swing.
You'll notice I'm sticking my bum out and my arms are coming up quite straight. Looks quite easy but do 50, 100, 150 of them, gets really tough. You burn lots of calories and it's really good for toning up, as well.
So, to recap, look at your nutrition and do some exercise. I recommend kettle bells but any exercise that you find enjoyable and fun is the best one for you. When attempting to flatten your stomach, always look at your nutrition to be sure you're not consuming more calories than you are burning.
Also, find an exercise that you enjoy and you will see results.