Currently, and for the last decade or so, I've had my own machine shop. I get to use all that trig that everyone always complained about back in high school on a daily basis. I get to set my own hours and don't get assigned all the crap jobs just because I happen to be the low man on the totem pole. I do those jobs, now, because there is no one I can pawn 'em off on. XD
I know, I know, having your own business and playing by your own rules seems like a dream come true, but there is a dark side. When you're working for someone else you don't have to take the work home with you, when you work for yourself you can't escape it. I'm tethered to it and can't just take time off to go fishing whenever I want, because someone might show up and need something fixed; something that has an entire operation and several dozen jobs depending on it. Sure, there is something about the feeling of taking a machine part that is no longer available and beyond repair -- making it better than original and seeing the customers jaw hit the floor in amazement, but then I have to deal with all the headaches associated with self employment. All the extra paperwork and planning for the future so that so that I don't become stagnant and have to close the doors like so many others have done.
Don't get me wrong, I love what I do, but self employment is not for the "faint hearted" or those that want to take it easy. Most days, it's from the minute you drag yourself out of bed until you fall back in at night in total exhaustion. I wouldn't trade it, though, for anything else I've ever done.