And how about a non-cliche answer?
(asked in friendliness)
Sometimes it is very difficult, having a little thing dependent on you for everything. No matter what, its needs must come first, so even if you have been up all night for any reason (such as the little thing wouldn't sleep and cried all night) even so, when that little thing needs feeding and changing first thing in the morning, you wake up and you feed and change it and you attend to its needs even if you feel like a zombie.
And that's if it's healthy. If it's sick, then there is a whole new level of difficulty that you could never understand until you live it. Because in addition to everything else, there is a terror that your baby might die and that there is nothing you can do to stop it. You would lay down your life to save your baby but even that might not be enough. So you give a doctor the most precious thing you have and sign papers letting them put her to sleep and slice her up, hoping that saves her life, but knowing that it may not.