Tummy Time Advice - using arms?

Any tips on how to get my little dude to use his arms more? He's plenty strong... He rolled at three weeks, but stopped around two months as he's now too long and heavy to roll without using his arms. He lifts his head and chest way off the floor, but he does the "flying baby"... No arms involved! I put him on the Bobby, and he just pushes with his legs until he rolls forward. It's like he wants to skip to crawling, but hey little dude... Gotta use your arms for that!!  Anyone have tips on encouraging baby push-ups?