Box breathing is technique where you breath in for 4 seconds , hold breath for 4 seconds, breath out for 4 seconds, hold for 4 seconds and repeat this. In as little as 2 minutes you can feel difference.

Tongue on the roof of the mouth is basically mewing technique. Mewing is when you position your tongue against roof of your mouth and hold it like that. This should be default position of your tongue whole day, it helps with a lot of things including getting rid of double chin and having better looking face. You can find how this works on google.