All children do that. Some are more gung-ho than others...like my oldest compared to my second child. They will hurt themselves from time to time, but typically nothing serious.
Tell me how do you suppose he is going to hurt himself seriously in his crib? Maybe get a bruise or a little knot on his noggin, but I doubt he could injure himself seriously.
He has to learn and explore. He has to get a few bumps and bruises. Let him be a boy. Nothing worse than a sissy boy whose mother over protected him. A little Lord Fontleroy that won't get his hands dirty, screams like a girl when he sees a bug, or cries like he's dying because he scraped his knee.
Just bite your lip and watch. Don't let him toddle off the edge of the porch or out into the street. You can kiss his ouchies when he has them, but then pat his head and tell him he's fine. Encourage him to shake it off. Encourage him to be a boy.
I was nervous all day the other day because my oldest went on her very first fieldtrip all the way to Rockford. I hated her being on that bus for that long and that far away, but I just prayed all day she would be fine. That the mom in charge of her little group would keep a sharp eye out for her and the others in her group.
THere is a line between being worried and being obsessive. There is a line between being adequately protective and over-protective.
Find the line for yourself and then grin and bare it. Will he play sports? That's the worst. Mine played soccor this year and I kept cringing every time she fell. If she looked at me, I just yelled; "your doing great baby...shake it off". She worked so hard. She was amazing. After a game she would have bruises and be so tired. I kissed her bruises when we got home and then told her how proud I was that she worked so hard and didn't quit.
It's hard to see your little one doing things that look dangerous. It is hard when you see them fall and hurt themselves. Our first instinct is to run over and scoop them up. Sometimes it is better to just walk over calmly and tell them they will be fine.
I seriously doubt he will hurt himself badly in his crib. It's in the living room that you need to worry! :) Just kidding. Now is the time to pad the fireplace mantle and put gates up at the stairs though.