Passage
Thou [my soul] hast said to Jehovah, Thou art the Lord: my goodness [extendeth] not to thee;
Thou [my soul] hast said to Jehovah, Thou art the Lord: my goodness [extendeth] not to thee;
Psalms 16:1 {Michtam of David.} Preserve me, O God: for I trust in thee.
Psalms 16:2 Thou [my soul] hast said to Jehovah, Thou art the Lord: my goodness [extendeth] not to thee;
Psalms 16:3 To the saints that are on the earth, and to the excellent [thou hast said], In them is all my delight.
Psalms 16:4 Their sorrows shall be multiplied that hasten after another: their drink-offerings of blood will I not offer, and I will not take up their names into my lips.
The verse centers on "thou", "soul", "hast", "said", "jehovah", "lord", and "goodness". It is saying that the verse draws attention to "thou" and "soul", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "Michtam of David Preserve me O God..." into verse 3's "To the saints that are on the...", so "thou" and "soul" 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 "thou" and "soul" with trust shaped by these words, not by a vague optimism outside the passage.