While saying the first paragraph of k’ri’as sh’ma, one may not motion to another, give tzedaka, or stand up for a rav or elderly person. If a child is making noise and disturbing, one may quiet the child (without speaking).
The Rambam counts the Kohanim ‘dressing up’ in their special bigdei Kehunah as a mitzvah in and of itself.
According to others, it is just a necessary step to be fit to do the avodah, but the Rambam holds it is a specific mitzvah for those performing the service in the Bais HaMikdash to wear special begadim, which create an aura of dignity and grandeur. This is reflected in there being halachos governing how we dress when we daven (siman 91 in Shulchan Aruch).
It goes without saying that this concept extends to our conduct and behavior in a Mikdash Me’aht.