He has the strength, the ability and the knowledge. It is just that he is unable to look down from up there. He can operate an excavator with his eyes closed, just by listening to his partner's calls. He can set up a demolition as safe as it should be. He can mix cement to any consistency you need, but up there where the air is thin.. His legs turn to jelly; his heart beats fast and his mouth becomes dry.
He loves his job though. He loves seeing the apartments slowly take shape, and he feels satisfied when he sees the new families moving in, smiling and excited. He takes no notice of how they only either ignore him, or look like he creeps them out.
He wonders what his mates think of him. Do they think he is not carrying his own weight? Do they have a nickname for him? He knows he is doing his best, but he also knows that the rest cover for him. He compensates by buying drinks and doing favours on the weekends.