The Pele Yoetz (נעם ויהי) writes, "Before every good deed... you must say the pasuk (Tehillim 90:17) ומעשה עלינו כוננה ידינו ומעשה עלינו אלקינו 'ה נועם ויהי כוננהו ידינו , "May the pleasantness of Hashem our G-d be upon us, and the work of our hands establish for us, and the work of our hands establish it.".
He explains: Each mitzvah has profound ideas, purpose, and kavanos, and we don't know them. Nevertheless, when we perform the mitzvos even in their simplest form, they will achieve all these secrets, but it would be far better to know the kavanos. Therefore, we request with the נועם ויהי that Hashem should consider in heaven as if we intended all the proper thoughts.
Pele Yoetz adds, "This pasuk, itself, has many divine secrets, with every letter and with every word, and it would be proper to say נעם ויהי on the saying of the נעם ויהי."
Kav HaYashar (ch.96) writes, "Have a lot of kavanah when you say the brachos for lighting Chanukah lecht. Say the brachos with joy because this is a very beloved mitzvah that comes once a year. Also, you should say the brachos with kavanah in honor of the holy malachim who came to your house for this mitzvah... The first brachah has 13 words, and one must think that he is arousing the 13 attributes of mercy. There are 13 words in the second brachah, which also arouse the 13 attributes of mercy. Together, they are 26 words, corresponding to Hashem's name (ה"הוי, which is gematria 26).... Malachim and Serafim come to the house of every Yid, and they watch his holy avodah when he lights the Chanukah lamps, and they answer amen to his brachah. A hint to this is that מלאך is gematria ן"אמ."
The Yaavatz (Mor Ketzia siman 672) says that the brachos on the Chanukah lecht are different than most brachos that we say before performing a mitzvah. The brachos on the Chanukah lecht are part of the mitzvah (because the brachos express the reason we light the lamps, so they are part of the pirsumei nisa) . The brachos turn the lecht into lecht of a mitzvah. Therefore, one must be extra cautious about saying the brachos with hislahavus, with the same enthusiasm he has when lighting the lecht.
