Passage
But the mercy of the LORD is from everlasting to everlasting upon them that fear him, and his righteousness unto children’s children;
But the mercy of the LORD is from everlasting to everlasting upon them that fear him, and his righteousness unto children’s children;
Psalms 103:15 As for man, his days are as grass: as a flower of the field, so he flourisheth.
Psalms 103:16 For the wind passeth over it, and it is gone; and the place thereof shall know it no more.
Psalms 103:17 But the mercy of the LORD is from everlasting to everlasting upon them that fear him, and his righteousness unto children’s children;
Psalms 103:18 To such as keep his covenant, and to those that remember his commandments to do them.
Psalms 103:19 The LORD hath prepared his throne in the heavens; and his kingdom ruleth over all.
The verse centers on "mercy", "lord", "everlasting", "upon", "fear", "righteousness", and "children". It is saying that the verse draws attention to "mercy" and "lord", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "For the wind passeth over it and..." into verse 18's "To such as keep his covenant and...", so "mercy" and "lord" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "mercy" and "lord" with trust shaped by these words, not by a vague optimism outside the passage.