Provide floor play opportunities that promote rolling, reaching or crawling utilizing pillow/bolster supports and favorite toys to motivate and engage your child to be active holding their head up. Assist them onto hands and knees and rock and reach for toys or encourage crawling races if independent. Playing games or reading books while on your tummy is great trunk strengthening for kids of any ability.

http://www.activelearningspace.org/implementation/motor-development/prone-activities