The tone of your letter will project your attitude to the reader. Although you can't hear it, tone in a letter has much the same effect as it has when you speak to someone.
Readers do much the same thing.
When the tone of a letter is cold or harsh, many times readers will put down the letter and pick up the telephone. One of the worst tone offenders in government writing happens when we refer to people as if they are inanimate objects. Nothing turns people off more than being spoken to as if they were just a number. The leg injury is disabling, therefore, the payee is entitled to benefits. A sympathetic opening should be used only when appropriate.