What does this Mizmor discuss?
Radak: It praises the ways of one who fears Hashem. Everyone in Galus should do so, and "see the good of (return of Hashem to) Yerushalayim" (5).
Malbim: It discusses good kinds of Hishtadlus that help.
What is a "Yarei Hashem"?
Radak: It is one who is careful about Mitzvos Lo Sa'aseh.
Malbim: There are three aspects of Yir'as Hashem - perfection of himself, of his household, and national. For himself, the primary happiness is of his Nefesh, that he goes in Hashem's ways.
Why does it say "Kol [Yerei Hashem]"?
Rashi: Because it says "Ashrei ha'Ish" (1:1), one might have thought that these rebukes and Musarim are only for men. "Kol" includes women.
What is "ha'Holech bi'Drachav"?
Radak: He is careful to fulfill Mitzvos Aseh.
Malbim: This is the primary happiness of one who fears Hashem - happiness of his Nefesh.
