My little guy hates tummy time. We only got him to do it by putting a sensory video on the floor in front of him. Now as soon as we put him on tummy (even without video) he rolls over on his back right away every time... it seems a little pointless to keep putting him on his tummy? He's doing ok with tripod sitting and should have that down soon. Should I keep putting him on tummy? My doc says yes but I don't see why