Tillie, I don't think you need to leave him to cry or anything, I seriously doubt he's not moving because he wants you to pick him up. Rolling, crawling and moving should all be innate to him. He should just do it (considering he's able to). Which is why it is a concern that he's not. Though like Tegam, I think all children meet milestones when and if they are ready. At this age babies don't take 'advantage' they don't undersand things like that yet. They want their needs met, and that is all. Not meeting milestones is something that is worrying because it could imply other issues.