Dora Bas Rivka Silver O'H
Psalms 146-150 - basically the rest of the Book - are a series that start and end with the word Hallelujah, a Hebrew compound word meaning "praise G-d!" These Psalms are recited every day as part of the morning service, immediately following Psalm 145 (which ends with a line appended from Psalm 115, segueing into the theme of "Hallelujah").
David says, "Praise G-d, my soul!" He continues that he will praise G-d so long as he lives. We should not place our hope in human beings, not even in those who appear to have power, because ultimately they have no ability to save. People can (and do) just drop dead, returning to the dirt from which they came. Instead, let us turn to the One Who promised Jacob that He would be with him.
G-d made Heaven and Earth, the sea and all of its varied life forms - G-d is in all these places! G-d's word is eternally true. He performs justice for the oppressed, He feeds the hungry and He frees the captive. G-d gives sight to the blind, straightens those who are bent and He loves the righteous. G-d provides special protection for widows, orphans and converts; He will frustrate the plans of evil people. He will rule forever, so praise G-d!
The Talmud (Brachos 12a) derives our practice to bend and straighten up in prayer from verse 8 of this Psalm: Hashem zokeif kefufim, G-d straightens those who have been bent.