When I was 37, I joined a sort of startup, where I was the third employee. We needed more programmers, and there was much discussion of whom to consider. Employees one and two had worked together and had many friends in common. One day Number two suggested, "What about Harry X?"
Number one replied, "No, he's a good software guy, but he's lost his nerve."
Actually, we did interview Harry X and made him an offer, but he declined to join us, saying he did not think we would make it. At the time, that's what I thought "loss of nerve" was about, fear of working for a company that might quickly crash and burn; but I was wrong.
Loss of Nerve was waiting for me when I hit my mid-forties. Programmers continually face dreadfully new challenges, new ways of working, and new rules that must be learned to accomplish anything. We rely heavily on "Tunnel Vision" to help us adjust to avalanches of new information quickly, and there's always a completely incomprehensible crash waiting to be fixed at the last minute. I believe most programmers are optimists - if we weren't, we'd never believe we could accomplish anything - but that optimism gets scratched and scarred in the face of so many new and strange challenges.
Software "Loss of Nerve" refers to a fear of conquering the continuously new unknowns, and a preference to stay with anything tried, true and safer. If I had a nickel for all the times I've had to coach myself, saying "Come on, you can learn that API; you can find that bug!" Well, I'd have a lot of nickels.