For a truth to be heard, it must be spoken with kindness. Truth is kind only when it is spoken through your heart with sincerity. You should know that when a message you convey to another person is not understood by him, at least one of the following things is true: what you have said is not true, or you have conveyed it without kindness.
The only way to tell the truth is to speak with kindness. Only the words of a loving man can be heard.
— Henry David Thoreau
To tell the truth is the same as to be a good tailor, or to be a good farmer, or to write beautifully. To be good at any activity requires practice: no matter how hard you try, you cannot do naturally what you have not done repeatedly. In order to get accustomed to speaking the truth, you should tell only the truth, even in the smallest of things.
We lie to other people so often that we get used to it, and we start to lie to ourselves.
— Francois De La Rochefoucauld
Truth cannot make a person unkind, or too self-assured; the manifestations of truth telling are humility and simplicity.