Besides being absolutely adorable, CJ and Will are really different. If you put CJ on his tummy before he was 6 months old, he would FREAK out - like totally freak out, kicking, screaming, crying... it wasn't pretty. Will, on the other hand, is totally mellow even on his tummy. I think Will did more tummy time in the first week of his life than CJ did in his first 6 months.
What I think is totally adorable though, is that CJ wants to do tummy time with Will now. If I get out the mat to lay Will on, CJ starts to say "mat, mat" and runs to play with him. Love, love, love how much he loves his brother...