My first job was in telemarketing. We were supposed to call people and convince them to buy a book full of coupons good for crap that nobody wanted. It sucked hardcore and I lasted 2 shifts, I was 16. I quit because the pressure to sell useless crap was incredible and impossible.
The next job I got was as a nurses aide at a old folk's home, still 16. It was okay. A lot of back breaking work lifing patients in and out of bed and chairs. Doing nasty personal things like cleaning and changing people. It was a bleak, bleak place to work. Luckily all the grub work they had you doing made the shifts go by fast and the money was decent, like $6 a hour. Back in like 85 that was top dollar! I learned and worked on a floor with patients who were moderately normal, old with some dementia/forgetfulness and illness. They moved me to a floor where the really hard cases of dementia and violent patients were after about 3 months. There was one guy they called a scalper because if he got ahold of your hair, he would pull it out. He didn't have any legs and was really violent. He had this incredible reach too because he walked on his arms his whole life. If you came near him he would swing at you, he was probably early 40's. I quit after working 2 shifts on this floor. The head nurse was like "you should of talked to me" when I told her how impossible I found it to work with such violent patients. I told her straight up that she was an idiot for putting a high school student on that floor rather than an adult. I was pissed.
I learned that jobs were jobs because they were tough and you got paid because it was work. In many cases, hard work for not a lot of compensation. I learned that I didn't want to have anything to do with commission sales or nursing (oh god, especially nursing).
My career is a bit of a fluke. I didn't expect to stay here this long. I enjoy my job and get paid very well. It isn't retail which is a definate plus. I like my job because it is as challenging as I choose to make it. If I want to take on extra projects, I do. If life is a bit tough, I can back off a bit and just do my regular thing. I have great benefits and I like my co-workers. After 12 years there is a bit of "grass is greener" feelings and some burnout at times but I recognize how lucky I am to have a decent job with great benefits.