Over time, I’ve found the right tone of voice for these assertions, too. It’s best to be insistent, but affable. Repeat yourself, but don’t get shrill. Speak to your darkest and most negative interior voices the way a hostage negotiator speaks to a violent psychopath: calmly, but firmly. Most of all, never back down. You cannot afford to back down. The life you are negotiating to save, after all, is your own.