I'd prefer not to be trapped in an elevator at all, now that I think of it.
As a kid (9 years old), I got trapped in a crowded elevator in hospital, visiting my grandmother. I panicked and got terrified. Think we were in there for around 20 minutes. I did not take elevators again.
At age 18 I started to study. I had to go somewhere during introduction on the 17th floor. It was a really hot day, and I decided that the fear for elevators had to stop there and then. So, with my whole group I went in the lift.
You can guess what happened. Crowded elevator, and we got stuck for 45 minutes.
But, since we still got out, I did give myself a task from that day on. I lived on the 5th floor of my flat, and I had to take the elevator at least once a week.
Took me some years, but it did work. I can take elevators without fear now.