Trying to roll

Jules looks like he is trying to roll. I have been helping him out by rolling him on the floor so he feels the motion. He now lifts one arm and leans his head over a bit, but it must be frightening to let yourself go into a full roll if you've never done it before. When I look at how far his head is off the ground now, it could feel scary for him to let it fall down and roll over! Here's a video of his initial 'attempt'!