I would like to take this opportunity
Dear Head,
Before I begin, I would first like to thank you for arriving attached to my neck. I am eternally grateful for your permanence because without it, I would have certainly (accidentally) abandoned you in some random public toilet or equally horrible place.
Head, we have traveled together now for quite some time, and I feel I haven't given you enough credit for all that you do. You have sustained injury upon injury due to Left Feet (they'll be getting a different kind of letter) and their clumsy shortcomings. I will extend apologies for them since they can't seem to get their act together.
On a more personal level, however, I would like you to know that I deeply regret the decision on multiple occasions to bang you into the wall. Quite frankly, I have no explanation . I only hope you will forgive me.
I'm sure you have kept the wild horse incident in your memory banks, and please know that so have I. I promise on my own life that we will never again (ever, ever) end a ride as part of a metal shed.
I also want you to know that I'm working diligently not to blame you for my every downfall and bad characteristic. I understand that while you are largely at fault and most likely the root of every emotional upset I've experienced, you always play some role in their solution. This is still a work in progress, as I'm sure you can understand.
In conclusion, my friend, I mean to say that I cherish your service and loyalty, and it would mean more than I can possibly say if you would accept my deepest regrets for all of the abuse that I have subjected you to thus far (future too).
With honest sincerity,
Me