Hi mummies, how to shed off those tummy fats after pregnancy?

I walk alot. Not walking around in office. I teach at student's hse which is juz walking distance from my house. I walk to and fro from Mon-Fri, every week. I ate lesser after giving birth as i'm too tired due to taking care of a super active baby. After giving birth for around 2-3 months or so, my stomach still feels hard. After 3rd-4th month, i started losing weight gradually. I didn't do any crunches or exercises. Juz walking alone as i'm too tired.. no strength to exercise! Not walking during shopping. It is useless!😂 Had water retention during pregnancy and my face and arms look swollen to me. Now, i'm very skinny like before. Lol. Hv to keep a balance. Walking and eat lesser rice. Thatz how i do it.