How come I cannot poop everyday even though I drink 10 glasses of water a day, and do a lot of exercising?

What do you eat? Stool (poop) is made mostly of bacteria that have digested the indigestible portions of your food (fiber, etc.). So, if your not eating much, you're not going to poop much, no matter how much water you drink.
Bowel movements. Every person is different in regards to frequency of bowel movements. Some patients do not have a bm every day. Staying hydrated and exercising is important but if you are not having other symptoms i would not worry about it. If you have symptoms, you can try increasing fiber intake and seeing a regular doctor.