Babies are naturally active, and their movements help them explore their environment. They first move involuntarily, based on reflexes, and then learn to move more independently as their bodies grow stronger and they begin to investigate the world around them.You can encourage their muscle development, strength and balance with simple activities done with infants as young as six weeks old.The first year of life lays the foundation for further development of gross motor skills as a toddler and preschooler. So get those little bodies moving!