I Can't Imagine

When I watch my baby, I can't imagine what he will be like in 2 months, 4 months, 6 months time. Let alone what he will be like a year or more from now.
All I see is who my baby is right now. It's hard to believe that soon he will be crawling and then walking. I can't imagine him moving! Right now, when I put him on his tummy or back, he stays there. He kicks and flaps his arms a lot, but he doesn't go anywhere. It just seems like he will stay like this for a long time, but it won't be that long, and that is so weird.

I can't wrap my head around it. And I'm starting to get that panicky, mom feeling of 'don't grow up so fast'.