I'm an engineer at an oil and gas company. I enjoy the work, and more than that I enjoy the people I work with, they're great. (Hasn't always been the case, but the team I'm on now I really like). The niche I'm in right now fits my interests, but its a niche that is a lot less necessary at <$40 oil. I'll probably do this for a few more years and then go out on my own doing something totally different, once my kids are in school, and hopefully have my mortgage paid off. Alternatively, I'll start doing something different right away after getting laid off.
I don't regret my career choice, it's worked out very well for me financially, I enjoy it, and I'm good at it. However, it does have repetitive days, and I don't like commuting. (I could move closer, but that would push the mortgage freedom date way out). I'm very much an "idea person" I always have lots of ideas for new businesses etc, and while I've executed a few of them as "side projects" or "do this to pay for university" type things, I definitely want to try starting a "real business" at least once. I'm definitely an odd choice for an engineer (I'm probably one of the very few who had higher English/Social Studies marks than Math/Science marks in school). I might try something still quantitative, but with more of a communication element for my next career, maybe in finance or real estate.