I'm a little afraid of the effects of stress on the long term. I'm 30, and I recently got promoted. I have lots of responsabilities, but I learn fast and I kinda got used to the job already.
On one of my first days at this new job, just before going to bed, my heart was pumping like crazy, I think it was arrhythmia (perhaps caused by anxiety?) This scared the hell out of me. I decided to quit a side job, this gave me more time to focus on my new responsabilities, and I'm not anxious anymore.