One piece of advice for a new mom?

Hi moms, would love to know what would be one piece of advice you would give to a new mom? A pregnant friend asked me this recently and it really made me think! I told her to try be as kind to herself as possible in what can be a mentally and physically challenging time - but afterwards I was wondering if that was just a bit wishy washy? Could I have said something better? Would love to know what other moms think or if there is any piece of advice that really stuck out to you?

I wish I had told people not to call for the first week or so, I was just so overwhelmed and in pain in that original period that while it was lovely to see people, it totally drained me.