Built a roof on a house last week. It involved a lot of lifting, climbing, and standing on very high and precarious structures. My hands are sore from constant mis-hammerings and heavy-object-droppings. My muscles are sore as well. So far, I haven't injured any of my bones or organs, but that doesn't mean it won't ever happen. It's the holding heavy objects still while standing twelve feet off the ground that sometimes creeps me out. That seems to be when I'm at the most risk of impaling myself on an upright two-by-four.