Jeremiah 29:11 is a well-known verse in the Bible. In fact, it is one of my favourite verses in the Old Testament. Note the different translations below:
For I know the plans I have for you," declares the LORD, "plans to prosper you and not to harm you, plans to give you hope and a future. (NIV)
For I know the thoughts that I think toward you, says the LORD, thoughts of peace and not of evil, to give you a future and a hope. (NKJV)
For surely I know the plans I have for you, says the LORD, plans for your welfare and not for harm, to give you a future with hope. (NRSV)
In using the word "prosper", I think the NIV is trying to highlight the extravagant grace of God for his people despite their sinfulness and disobedience. Israel was going into exile because of their sin, but Jeremiah prophesied that God would restore their fortunes in 70 years.
Unfortunately in our Western world today the word "prosper" carries a connotation that (I think) does not reflect the Hebrew word in the original language. Today, to be prosperous often means "to be wealthy and affluent - primarily in terms of one's material possession and success in the soceity". Also, prosperity in our world today is often measured by the excess wealth and luxuary people enjoy. This meaning (ie. the excess ownership of material possession), I believe, does not reflect what Jeremiah says.
The Hebrew word used in the passage is shalom. What is shalom? According to the usage of the word in passages Isaiah 32, 65 and Ezekiel 34, shalom seems to refer to wholeness and well-being in all our social, ecological, political, agricultural and economical relationships, which are in turn rooted in a restored covenant relationship with God. It is about peace, security, wholeness and well-being in all relationships. It is about what we can experience in Christ as we seek to love God and one another here on earth now, but its final and complete realisation will only take place at the final renewal of heaven and earth.
So let us take comfort in the fact that the LORD knows his plans for us - plans to give us shalom! But let us not turn this into a self-centred pursuit of pleasure and prosperity, which is a temptation in our materialistic and individualistic world today.