Tummy Sleeping???

Ok, so I know that "they" say that baby's should always sleep on their backs but what do you do when you baby sleeps better on his tummy? When we were all growing up our parents always put is on our tummies and we are still here right? I am absolutely TERRIFIED of SIDS but Brody sleeps SO much better on his tummy it seems. I don't put him on his tummy very often, usually the second time he wakes up which is anywhere between 5-7 am I will put him on his tummy to go back to sleep and sometimes for naps if I put him on the floor on a blanket or his play mat thing on his tummy he falls asleep better. I don't want to put him at risk for SIDS but I also want him to get good sleep so what do I do? Advice appreciated!!