Because you'll need it. You know that cinematic image in your mind of the mother you think you are going to be — the one dripping with attentiveness, awe, and unwavering patience? How you will lovingly nurse and rock your swaddled baby to sleep in the peaceful stillness of the dark hours night after night? I hate to throw cold water over your hopes and dreams, but it is likely that every moment isn't going to look like that. And you absolutely must forgive yourself ahead of time.
We forgive others for so many missteps throughout our lives — the lovers for their indiscretions, the friends who disappoint us, and the bosses who take advantage of us. But so often new moms do not forgive themselves for failing to live up to the fantasy of the mother they thought they would be. Please give yourself the same loving compassion you would give a dear friend who is trying their best.