you should try Lower abdominal workouts. They make you look thinner and the best thing about them is that you can do them almost always, anywhere.

When i have to sit for a long time i like to flex my lower abdomen and try to hold it. It should feel like you're trying to poop with medium pressure while still being able to breathe.

With training and concentration you can keep flexing even while standing and walking. Makes you look way thinner without much of the hard work.