Why I shouldn't be allowed to use tools

So, I went to Habitat for Humanity today with my dad to work on a house. We worked on one back in the fall, and didn't get to finish for one reason or another. So, they just started the spring build and were able to go today. It obviously requires the use of tools, and I'm fine with that. My dad is very patient with me, and helps me figure out what I'm doing, and finishes it when I can't do it. I'm not very strong, and my muscles get tired very easily. Here is a good example of why I shouldn't be left alone with tools.
We spent our whole day putting in nailers. For those of you, like me, who have no idea what that means, I shall explain. We put 2x4's on some of the framework, sticking out over the ledges, so that they had something to nail the sheetrock to. They don't actually nail it, they screw it, but as the green hat(leader guy) said, "We don't call them screwers." Haha, I thought that was funny, but anyways. So, we were often hammering the nails in in funny positions. We would be on a ladder, in between 2 joists, with our arms wrapped around one of the joists - so that we could reach the nailer we were nailing in. Well, My dad was off cutting a new piece, and I was finishing nailing one in. I wasn't at a good angle, and had gotten a nail bent (that happened a lot) so I tried to fix it. The nail was right in front of my face, and I decided to use the claw side of the hammer to pull it back straight. Normally this would be fine, except for the fact that I was directly in front of the hammer. So, when it didn't move the naile at all, the hammer had no where to go but my nose. That's right, I hit myself in the face with a hammer. I'm pretty glad that I was by myself and up high where no one could see me. It hurt (needless to say), and it pushed some tears out. I was understandably shaken, and kept checking to make sure there was no blood. I mean, how am I supposed to know its broken? The only way I know is, it normally bleeds right? (That's what happens on TV!) It didn't bleed, so I figured it was alright. I didn't tell my dad til we left, and it really had stopped hurting. But now, the pain is coming back. I don't think I hurt anything - its just bruised. So, now I make sure my face is out of the way, whenever swinging the hammer. (You'd think I would've already been doing that.)