How do you actually stop reacting to short-term noise when half your portfolio is exposed to it?

Three years in and I still can't stop reacting to news... Almost dumped an 18-month-old yesterday on a tariff deadline that probably doesn't even affect them. I've taken two bad swing exits this quarter on headlines that turned out to be nothing. Re-read my thesis, calmed down on the hold, but the swing exits already happened. What actually got you to stop reacting?... Process, screwing up, or just getting older?