Postpartum Fitness: What should you expect?

Today is technically "Workout Wednesday," but I'm breaking tradition to send you over to Kate's blog. She just welcomed a beautiful baby girl into this world, and I'm helping her out with a guest post. If you're a new mom or a first-time mom-to-be, you'll be especially interested in the following:

Question: Moms, what surprised you the most when you returned to fitness after your baby was born?