Of course we get stressed out sometimes, we can't be perfect at everything we do. But don't worry about it just do the job. The more you think the bigger tha chance to mess up. Me I do lot of semi trailers and i remember the first one that i've done i was nervous as hell, bacause of the rivets but once i started working i forgot about it and did a good job, not perfect but good job for first time, and customer was happy.