I've been seeing these 3 week post partum celebrity moms working out and looking like they never had a baby and it is a bit disturbing. First of all, most doctors won't clear 'normal people' for exercise or even sex until 6 weeks post partum. Secondly it often takes 6 weeks or more for your uterus to return to normal size, 9 months to lose the weight it ook 9 months to put on, etc.
My concern is for teens that lately seem to be thinking pregnancy is 'cool' and your body suffers no permenant changes because of it. I know everyone is different but thinking you can get on a treadmill or back to the gym when your baby is 2 weeks old and look back to 'normal' a month later sounds like a recipe for post partum depression and an unhealthy self image.
I may be a teensy bit jealous being that pregnancy really changed how my body works and I'll be on meds forever because of it