I have gained alot of weight with my first born, I was very petite before being pregnant, I was…

I have gained alot of weight with my first born, I was very petite before being pregnant, I was always between 120-130 after I had my son I stayed 140-150 and um pregnant with baby #2 what is the best way to lose weight once.i have my daughter !? I also will be breast feeding with her, I know thay can help you lose weight