Unconscious avoidance/fear

I noticed sometimes on the freeway that even though it's the weekend, a lot of cars wouldn't take the carpool lane. They are contend to be tightly spaced at 55mph on the other lanes rather than taking the carpool lane. People are so used to not driving on the carpool lane during the weekday commute hours that they automatically avoid using the lane even when they can. Whatever we used to avoid or used to fear become a habit that we no longer re-examine and continue to reinforce.

Another more telling example... An experiment was done where they put a shark in a large tank with a small school of fishes, but divided the school from the shark with a thick piece of glass. Naturally, the shark chased after the small fishes but each time just as it got close, it would hit the dividing glass and hurt itself. Everyday, the shark tried. Everytime, when it thought things would be different, the result was always the same. After many days of this, the shark started to stay away from the small fishes - which now represent pain instead of food. After a while, even though the dividing glass was removed, the shark wouldn't even try to eat the small fishes that swam right in front of it.

I think you know what I am trying to get at.
Do you unknowingly avoid or fear something?
Have you ever examine all your fears and the assumptions behind them?