How to continue tone areas of your body during pregnancy?

Kenzy
I had been active all my life, but then I got pregnant towards the end of high school and stopped doing sports and gained a ton of weight with my first pregnancy. Had a second kid two years later and did decent with my weight gain only because I was sick all the time. But, it still left me with 100 lbs from my first pregnancy pre-weight. I managed to lose 30 lbs. Recently and found out that I am now expecting again. I don't want to gain all that weight back. Plus, I would like to continue toning my body while pregnant so it isn't so hard after I have the baby? HELP!