Valsalva maneuver works as well as benzos.

Yes, you read it right. I was on the verge of having a full on panic attack while in the shower. My heart rate was about 2.5x my baseline. I decided to inhale some air, brace my core as hard as I could, hold my breath, contract my diaphragm as strongly as I could without letting any air escape, then I squatted really slowly, stopped for about 5 seconds at the bottom and then quickly rose back up, exhaled the air and started breathing normally once again. My heart rate went back to normal in less than a minute and the anxiety was entirely gone. This happened less than 30 minutes ago.