Weight loss

So I’m trying to lose weight I have 35 pounds I wanna lose. Is it possible to lose weight from just eating right? I try to exercise but it’s so hard to some days with having a newborn and being a stay at home mom. I eat healthy and drink a gallon of water a day is it possible to lose weight? Or do I have to some how fit in exercise? And how long of exercise should I do? I was hoping to lose 20 pounds by Christmas but i don’t know if that’s gonna happen