That simple fact really can simplify life. We are called to obey God's will for our lives, and we are also called to seek God Himself. I personally think that the big issue is whether we are truly seeking God and trusting Him. It is a bit difficult to do God's will when we are seeking for what we think God's will should be -- when He has already told us what to do. Right now in my own life, I don't know for sure exactly what my next step is going to be (I'm graduating in a few months), but I do know that I need to seek God. Psalm 27:4 states fairly clearly what I mean by this.
Anyhow, in the Jeremiah 29 passage, God is speaking to the nation of Israel, telling them that He has a good plan for them. I believe the same is true for any of us today as Christians, if in our hearts we seek Him as the second part of the passage states.
Since I'm talking about God's will, I think I'll go ahead and carry on for a little while about some things that really bother me about modern Christianity's views concerning God's will.
Have you ever met people (possibly yourself??) who constantly have to battle with thoughts of having "destroyed" God's will for their lives? Even though they are born-again Christians, they may believe that something that they have done in the past has forever robbed them of the privilege of being in the center of God's will. Well, if we could mess up God's will for our lives, God wouldn't have a plan or will for any of us! We all have sinned (Romans 3:23). But, God knows the future, and He knows when we will make mistakes and sin, even though He doesn't count that sin against us! And, I believe firmly that He still can make good come out of any circumstance (Romans 8:28), and we must ask forgiveness and continue to seek Him.
This does not mean, however, that we live consequence-free in this life. We still do reap what we sow in this world, and we have the freedom to really mess up our lives if we should choose to do so. Does that mean that God makes people mess up their lives? By no means (James 1:13)! We are called to obey Him, and obedience springs from love (John 14:15), and love from an intimate knowledge of God (I John 4:7-8). Unfortunately, I cannot explain with my limited logic every aspect of an almighty and eternal God, so I have no fully reasoned explanation of how God's Sovereignty and our responsibility interrelate. But, the Bible teaches both, and we must all fully accept both.
Be encouraged, knowing that God knows what He is doing in your life (Romans 8:29-30), and you can trust Him day by day, because He is perfect, even if we from time to time choose not to be.