My ped shared that
there are a few things, and I think there were 4, even though I can
only remember 3, that we cannot control--sleeping, eating, and going
potty.

I'm really not convinced, I mean you can't control whether you have a
child for whom is naturally easy to fall asleep and to stay asleep or
one for whom it is the complete opposite - so you can't suddenly make a
child who's not that way inclined sleep 12 hours each night, but you can
optimise their sleep, by insuring you are getting the right time for
bedtime, providing a good environment for sleep, reacting appropriately
if they wake at night, etc.

The same goes with potty training, you can't change the point in time at
which a child will have the physical ability to do it, but you can
respond quite differently to the early signs they are getting there
physically and it's highly likely they will affect the long term
progress of potty training.

Cheers

Anne