I have always been impressed by the unflappability of my friends who work as paramedics or in mountain rescue. If you are going to be able to help people in distress and facing extreme challenges you can't get bent out of shape by life yourself. Getting all macho and controlling because of your own fears would just make things worse. Paradoxically real strength exhibits itself as gentleness.
While I wouldn't want to compare the responsibilities of driving large trucks with saving people's lives there are similarities. You are responsible for a very large and very dangerous lump of technology, very often in public spaces. Allowing your fears to get on top of you makes you more dangerous. Precision calls for a gentleness and concern for your immediate environment. Throwing your weight around, literally, makes you a liability.
I have been struck by the consistent kindness of the drivers I have met and been helped by. They share the unflappability of my friends in the emergency services. Their gentleness is something I aspire to. I want to be like them when I grow up.