Some people walk into a tense room and absorb the mood. Others walk in and change the forecast. Practice being the second one.

Rooms hand you a mood at the door and most people take it without noticing. Absorbing it is the default, because matching the energy around you requires no decision at all. Changing it takes a deliberate second where you choose what to bring instead. That is not fake cheer, it is refusing to let a room write your part for you.

Pause the next time you step into something tense, before you say anything. Decide what tone would actually help and put it in your first sentence. One person doing this shifts a surprising amount, and nobody there will know why it got easier.