to become too frightened to do something
何かをする勇気を失う
"I was going to ask her out, but I lost my nerve."
"彼女をデートに誘おうと思ったけど、勇気を失った。"
to lead by example, taking the initiative
to appear or arrive dramatically in a situation
to control your emotions and behave calmly
to talk too much and for a long time
an early warning of potential danger
to start over again because the previous plan failed