[Avodah] To Stand or Not to Stand for a Chosson and Kallah

[M Cohen]

RYL asked  .. If it is indeed the case that we stand when people are going
to do a 
mitzvah,  then why don't we stand when the Baal Kriah gets up to 
lein,  when the Baal Shachris goes to the Amud to daven,  etc. ?

indeed, r Yaakov kamanetsky writes that the minhag to stand for az yashir 
in pesukei d'zimra is to honor those going to give tzedah at that that time.

Mordechai cohen

As for your question, what mitva/chiuv is Baal Shachris davening, Baal Kriah
leining,  etc ?