Grace and peace to you from God our Father.
Paul's desire was for these believers to experience God's grace and peace. Peace is something we all want. The peace of God does not mean smooth sailing in life, but it does mean that we can rest in the knowledge that we have peace with God and He is in control of our life.
Since Paul is writing to people who are already believers, he is probably not referring to peace with God - they already had that. He wants them to experience the peace which comes from an increasing knowledge of and relationship with the Father.
This is a peace that we can enter into as we continue to develop our relationship with God. When we are feeling overwhelmed with the situations of life, we need to focus on the Grace and Peace of the Father. His loving arms are around us, no matter what waves are crashing on the beach of our life.