Simply replace the unfilled areas such as "" and "[date]" with your information.
I have been dreading this day for some time now because today is the day I have to say goodbye to you. Now that the day is here, my only wish is that these words will ease your pain and express how truly special you are to me. I have been presented with a once in a lifetime opportunity. Moving to [destination of move] is not only important to my job, but it is a key step to becoming the [career goal] that I have dreamed of being.
As I embark on this journey, please know that I will always hold you in my heart. In many ways, you have helped me to achieve this goal. Your faith and support has given me the courage I need to succeed. Now it is time for me to believe in myself and take this next step.