Is mobility good when you are under one?

For the last week Jaxon has crawled a couple steps and then his legs give out on him and he falls and then continues to army-crawl. A couple days ago, he has finally done it. He is a crawling machine. He is all over the house. He doesn't just want to crawl though...he wants to walk. He is always pulling himself up onto things and trying to stand. He has a walker that he absolutely loves. We practice walking with him and he always has a huge smile on him face. When he crawls, he tries to get up on his feet. He is going to be walking before I know it. He is growing up way too fast. The other night when Ryan and I were putting Jaxon down for bed, he was screaming, so we went in to check on him and we found him sitting in the corner of his crib. He is figuring out to do so many things. Why do they grow up so fast? I hate it.