It is completely normal for some babies to reach rolling and mobility milestones at different paces. To encourage movement, prioritize frequent tummy time on a playmat, which helps strengthen their core and neck muscles. You can also engage them with mirror games to boost self-awareness or try gentle 'guided' movements by helping them roll sideways while they are on their playmat. Always consult your pediatrician if you have specific concerns, but rest assured that many babies simply need a little more time and practice to master these motor skills.