I had a full time position as a Digital Media Marketing Intern at a business IT consulting firm. I was the only one under 40 without a Masters or BBA and I wasn't being paid for my work, yet I was demanded to work just as diligently and without any guidance. My boss was an ass but he was nice enough to take us to lunch sometimes.
I was responsible for the re-branding of the company and designing/managing their website after the previous intern was fired for being too incompetent. I did my best and made my boss happy, but it was the the expense of my sanity and social life. I worked from the moment I woke up, to when I went to sleep. My work always had to come home with me because there were not enough hours in the day to complete it all at the office. I started getting panic attacks at home from reading my boss's emails.
I became an alcoholic at work, using my lunch breaks to down 3 pints at the bar across the street on a daily basis so I could make it through the day without having any mental breakdowns. I didn't feel like I was learning anything new, only that I was being used a free labour. After 8 months, I finally quit under the pressure. I hated working there and dreaded having to go back everyday.
It helped me realize I don't belong in an environment like that, now I'm looking into trade schools for plumbing. Office life can suck it.