What are some good and quick exercises i can do to tone up my lower belly area? I lost most of the…

What are some good and quick exercises i can do to tone up my lower belly area? I lost most of the baby weight but now i just need to tone things up again so my stomach is flat like it used to be. I eat healthy already so thats not the issue. I dont have a whole lot of time to work out either. I dont believe in weight loss supplements or waist trainers either, so please no comments about that "It Works" stuff. Id rather tone up the natural way. Thanks in advance!