Just keep very hydrated, and listen to your body. If it says enough, take a break for awhile. Good luck with your pregnancy!
Oh yeah, I know. I don't want to lose weight or anything, just heard exercising is good during pregnancy. Was going to walk on the treadmill or something simple.
You can do anything you did prior to pregnancy, but should limit (or avoid) cardio and lifting weights. Remember as well that it's great to stay in shape, you do NOT want to do this to lose weight, nor should you limit your intake of food.