Why did he say "Anah Hashem"?
Rashi (Yeshayah 38:3): Where is Your mercy?
What is "His'halachti Lefanecha"?
Radak: It is Avodah of the heart.
Malbim (Yeshayah 38:3): This refers to his intellect. (a) It was "b'Emes" - I did not believe in folly. (b) My deeds were "b'Lev Shalem" - only because You decreed, and not for benefit of the body or soul (reward).
What is "veha'Tov b'Einecha Asisi"?
Radak: This is his deeds - "va'Ya'as ha'Yashar b'Einei Hashem", "va'Yishmor Mitzvosav" (18:3, 6).
Radak citing Brachos 10b: He hid Sefer ha'Refu'os of Shlomo, because people relied on it, and did not seek Hashem in their hearts.
Malbim (Yeshayah 38:3): I did not let impediments stop me from carrying out good deeds.