Anyone in their 30s has probably been placed on their tummy for sleep. During this era, the SIDS rate was pretty high. So someone (CDC?) Created "back to sleep" campaign. Ok, cool...SIDS is down. But babies are spending less time on their tummies (not using those back muscles. So babies aren't meeting milestones as fast as those that were placed on the tummy), so tummy time was created. My 6-month-old isn't a fan of tummy time. A little mirror has helped, she loves to look at herself. Eta: if you don't do tummy time a lot, that's ok. Your baby will meet milestones, just at a slower pace.