In Jeremiah 29-33 we find a God who calls His people to invest and to be a light in the midst of exile and pain. They can do so because their hope is in the God who will restore.
But when we look further, we see that restoration and a return to the land God had promised comes when the covenant is fulfilled by Jesus.
We, too, can invest and be light in the midst of exile and pain because we know that Jesus has come and fulfilled the covenant and will some day restore and redeem the earth...that we can inherit the new heaven and new earth.