Need to lose weight

I was told by my OBGYN today that I was overweight and I agree I used to weigh 151 in the beginning of my 1st pregnancy then went up to 185. From there I went from 185 to 218 in my second pregnancy. And now last time I got checked I was 230 but went down to 213 but I'm at 250 right now. Idk how I walk every day at least for an hour. Idk how to lose weight the reason I lose weight so fast before my first baby was cause I had so much energy I used to cut the soda out and ate slower and walked and played basketball with my nefew for at least 5 days a week. Any advice ladies please I don't want to reach 300lbs. Doctor recommended 45 minute workouts 5 days a week.