S.W.
Echoing the other moms' advice - our doctor told us at our 4 month checkup that our son's default position when playing on the floor should be the tummy. That way we can hold rattles or mirrors to the side and above him to teach him to turn and hold his head. After doing this for just a few days, our son no longer fussed when on his tummy and quickly learned to roll over from tummy to back!