"Times of refreshing in the presence of the Lord..."
Remember that this spoke of the relief that comes at the end of a plague. A relief like that of a cool rain on a dry and weary land. How much has sin cost you? How much has sin worn you out? How much has sin taken away? Do you feel enslaved by it, like you just can't get away from it no matter how hard you try? The apostle told the people, if they turned to God, they would experience relief. In context, the people had crucified the savior. They must have in this moment of power (the lame beggar is healed), been reminded that they were personally responsible for the death of the one who had come to save them. They could be haunted for the rest of their lives by this heinous crime. But Peter says, "turn to God...experience times of refreshing in the presence of the Lord (the very one they had crucified)". What an amazing thought! If God could do this for those who crucified His Son, what could He do for you in your life?