The desire of lots of people is to have a flat stomach. Sadly, you cannot just exercise your method to it. A lot involves exactly what you put into your mouth. Do you have excess fat in your abdomen location and want to get rid of it.
After suffering a shin splint, and two hamstring injuries years ago, it has affected my both my flexibility and practice a lot. I know I cannot overstretch and I have to be extremely careful in my practice. Splits are not my best because of that.