This letter offers your best wishes to someone who's dropping out of the rat race to play golf or study tai chi.
1234, Main Street
Boston, MA 02123
07 April, 2005
<Recipient Address Goes Here>
This is just a note to wish you all the best as you retire. After all the hard work you have put in for so <years> years, it's nice to see you come to this point in your life. It must be wonderful to know that you now have the time to do all those fun things you've had to put off for so long. I hope retirement will be for you a time of discovery and fulfillment.
Congratulations on reaching this important milestone. I wish you every happiness as you retire.
encl: <List of enclosed items goes here>