If fear causes you to alter the way you live your life and celebrate your accomplishments, the terrorists have won.
After 9/11, the messaging was, "Go out, live your life. Go to work, take your kids to the park, take a walk or jog, and don't be afraid."
Sure, exercise a bit more safety and alertness, but don't be afraid to do the things you want.
Trump didn't cower under the podium until the threat was over. He jumped up and yelled, "Fight!" That's how you defeat them.