Q Many people like to quote Jeremiah 29:11 as a personal promise from God to themselves. Is that belief justified?
A There is no question that God had Jeremiah write this verse—“For I know the plans I have for you . . . plans to prosper you and not to harm you, plans to give you hope and a future”—to exiles in Babylon (29:1, 4). He assures them of his plan to bring them back to Judah some 70 years down the road and thus "fulfill [his] good promise" (29:10). The promise is specific to them in their time in history.
But the Bible reveals that this return to Jerusalem is also part of a larger plan to bring God's only Son into the world to rescue us from our sin. Beneficiaries of this plan are not limited to exiles in Babylon. In the fullness of time, in Christ, God reconciled us to himself, creating a new humanity. By sheer grace we are included. We too have been given hope and a future.
As long as this history of redemption remains the primary focus, I see nothing wrong with including specific ways in which God has given us personally the riches of his grace. It isn't an either/or. "Because I belong to him, Christ, by his Holy Spirit, assures me of eternal life and makes me wholeheartedly willing and ready from now on to live for him" (Q&A 1, Heidelberg Catechism).
To say that Israel's God through Jeremiah had only you and me in mind is out of bounds, of course. But we may notice within ourselves “the unmistakable fruits of election pointed out in God's Word” (Canons of Dort I, 12).