A phrase or a word for saying a nice thing just for its sake

Context: Suppose you are thinking of doing a task long due for quite some time, and you decide to do it today. But then, someone else also tells you to do it, and you want to say that you were also thinking of doing it today (and so you’ll do it).

Now, it’s not uncommon to say that even if that wasn’t the case, just to be nice. But you want to convey the other person that, you’re not saying this just as a formality / just for its sake, but you were actually thinking of doing it.

Is there a word or a phrase that conveys the italicized part? Yes, just the italicized part, I am not looking for an expression that conveys the entire thing.

Note that I’ve looked at this question, but the OP didn’t provide much context, so the answers are not precisely what I am looking for. (This answer does sound close to what I want, but I looked it up, and it’s not very precise)