I loved this article posted by Scholastic about the top 5 physical benefits of reading for children. 

They help kids “see”
Kids play out the story in their heads, consciously and unconsciously — and that can boost their imaginations. Ask questions about what things look like so your child can visualize in greater detail.

Books sharpen the senses 
Reading words like garlic can trigger smells while metaphors like a slimy person can call up textures — often at the same time. Experts think reading may give kids a richer, deeper experience of the story and possibly even the world.

They get kids moving 
Just as we see a story in our mind’s eye, we also automatically play out the action in our heads when we read “Harry kicked the ball.” Running through actions in your mind improves your ability to do the same thing. (It’s why athletes can bump up their game by imagining themselves, say, making a free throw.)

Books grow brain cells 
Struggling readers have fewer cells in some regions. But a study found that after six months of daily reading, the weak spots beefed up so much that the kids’ brains looked the same as those of kids with stronger reading skills.

They make the heart bigger  
Preschoolers who hear more stories get a head start on becoming more empathetic. That’s because kids’ books are packed with characters who air their feelings — 
and because parents tend to talk about the characters’ emotions.

Sources: Benjamin Bergen, University of California, San Diego; Raymond Mar, York University, Toronto; Krish Sathian, Emory University, Atlanta