I like to give examples to my students of why yoga asana practice in the studio is also practice for life. It's an important moment when they realize that they probably can do something (say a backbend or a handstand) but they are afraid of it. They're physically ready and able to do the pose, yet it still brings up fear. I almost always say the same thing. Asana practice is a good place to practice doing what you're afraid of every day.
I'm not talking about being afraid of injury or a fear of straining something by doing a pose. That's an entirely different subject. I'm talking about unattached elemental fear. In practice we learn to do what we're afraid of despite the feeling of fear. When that process is familiar it's something that accompanies us into the rest of life. A feeling of confidence builds when fear comes up and you stay with the practice. This has been one of the greatest benefits of yoga practice for me. It's both an exhilarating and humbling practice and I have at least a lifetime's worth of work still to do!
I came across this great quote in a book by Kathy Dobie. It was attributed to anonymous in the book. "No interesting project can be embarked on without fear. I shall be scared to death half the time."