do (something) out of the goodness of (one's) heart

To perform some task because of one's altruistic generosity or goodwill, without personal or ulterior motivations. Often used in negative constructions. You expect me to believe you would do this out of the goodness of your heart? Come on, what are you looking for in return? I'm not helping you with all these different jobs out of the goodness of my heart. I fully expect to be paid for my time. Please, no lawyer just does something out of the goodness of his heart. Don't be surprised when he bills you for this.