I've met mothers that go in to it with pink little glasses on their noses and daydreams about being a happy, well rested and beautiful parent of a happy, healthy, beautiful baby. When things don't go exactly as planned they get depressed and scared about their thoughts. It's important to know that it's totally ok to sometimes feel like you want to go back to when it was all so easy and you could sleep, shower and go to the loo when ever you wanted. This is not to scare anyone, it's to make people understand that it's ok not to always be so damn happy and cheery. It doesn't mean you love your baby any less or don't want her around anymore or most importantly, that you're a bad mother. Most mums go through these thoughts at some point. Actually, I'd like to meet the kids of a mum that says she's never ever felt totally hopeless. They must be total angels

So again, at times it hurts, you'll get tired, you'll get mad and you'll feel totally helpless, but still beeing a mum is the most fabulous thing you can ever think of and creating life and raising kids is the greates miracle ever, the love you feel for your kids will overwrite everything not so great in the end.
And to avoid any misunderstandings I'd like to state that this is my view on motherhood and is not meant to undermine any kind of mothers, fathers or people that raise kids in any kind of circumstance.