“The Zohar HaKadosh writes that [the mitzvah of Bircas HaMazon] is very beloved by Hashem. When a Jew says [it] properly, he brings indescribable joy to all of the Upper Worlds. We are supposed to say Bircas HaMazon as if it is our greatest zechus [merit],… singing with joy for the opportunity [to thank and praise] Hashem for the bounty He gives us.
Many Tzaddikim said that we should look for opportunities to eat bread just to be able to say another Bircas HaMazon. Those who recite it properly will merit a special place in Gan Eden [where the souls rest upon leaving the body].
A person should say Bircas HaMazon slowly, word by word, as if he is counting precious pearls. He should have the same amount of desire to say Bircas HaMazon as he did to eat his meal when he was hungry.”