At a recent baby shower, I was invited to give "parenting advice" for the mother-to-be. I gave advice that was useful, but not very insightful. As the evening wore on, I wished I had said something entirely different because I felt that motherhood sounded more and more like an ominous burden.
So, my advice to all the mothers-to-be out there would be: Enjoy your kids! Yes, they're going to be screamy. Yes, they're going to be poopy and drooly and gooey in general. Yes, you're going to need a break every so often. But don't let getting away from your children be the highlight of your life - because then being with them becomes drudgery.
I think what is hardest about being a full-time mother is how many different tenses you have to live in at once. You have to be in the present to enjoy it fully because if you're always rushing here and there and needing to be on time and life is generally just filled with Things To Do, you often miss out on the tender, wonder-filled, charming moments that pop up most frequently when you're not "doing anything" but Being with your child.
You need to live a bit in the future to remind yourself that everything passes to keep perspective on the relative smallness of all the disasters happening daily (your shirt is peed/pooped/burped on for the 317th time in one day; your child decides that it's a good time to experiment with heights and decides to throw his cup, your plate, and himself off the table; your child is feigning deafness when you ask her to pick up the toy/book/blanket). But not too much in the future because if the things you planned on don't get done, frustration inevitably sets in.
It would be nice to always live in the present perfect tense and the future perfect tense, but those imperfect tenses are also necessary, useful, and yes: enjoyable.