I think at first I was pretty well prepared as I had done some babysitting etc (this in no way compares to looking after your own little one 24/7 I know, but it helps you with the basics - bottles, nappies etc). I wasn't shocked with the amount of work at first, but my body was! because you're so drained emotionally and physically it does feel hard - I spent the first week or so in what I like to call "zombie mode". I can remember the health visitor coming round and to this day, I couldn't repeat half of what she said, I was sitting there in a daze with my eyes almost closing.
Id say it gets easier, not because of them as much but because you just get used to being so tired and not having a lot of time to yourself, then their sleep routine gets better which is obviously going to have a huge effect on you. I didn't get dressed or stop napping in the day for a good few months though, I felt well and truly drained. I guess it also depends on your circumstances - for example, we live with my boyfriends family and that has also drained me at times, so has a knock on effect for everything else in my life.
You need a balance and things will feel much easier. She is your baby and im sure you completely adore her, but try not to forget about yourself.