I'm reminded each day, as I pin/wrestle my toddler to change her diaper or remove her shirt, that being a mom is a physical job. A really physical job. On days when I'm out with both kids alone, when I quit after bedtime, my shoulder aches from the one-armed hold. When my first daughter was a speeding toddler, I remember it was my elbow that hurt, especially when my husband was out of town and I'd spend the weekend alone with her. Lifting, tossing, lifting, redirecting, and lifting.

This came as a total surprise to me — especially as I have always loved the physical. I was a hardcore tomboy, an active athlete through high school and college, and am still someone who loves to move via running and soccer and hiking. I was able to swim during my first pregnancy, after jogging the first 20 weeks, and while I'm sure I lost some fitness, I still wasn't prepared for the rigor of motherhood. I thought I was strong. Not at all.

When I was pregnant, I focused on the idea of having a child, of course, and to me, this was a relationship. I worried and thought about yes, caring for a child, but I thought in the sense of being informed and emotionally involved. I thought about loving her and I thought about keeping her alive. I read books and maybe, just maybe, I pictured myself holding a little baby. We'd take leisurely walks and lounge in parks. (And we did.)

What you don't, or can't quite picture, is that a baby actually weighs something. Mine arrived at a solid 8 pounds. They squirm. You can't even picture the fact that you may not actually be able to put the baby down. You can't picture wearing the baby for six to eight hours a day. You can't picture holding the baby in various awkward positions while nursing for other countless hours. Especially at night. You can't picture bundling her around while soothing, while dancing, while cuddling on your shoulder, while reaching into and out of cars and strollers or while holding arms straight out, covered in milk or poo. You forget to picture these things. You also do not picture the reality of doing things one-handed while holding baby — like feeding oneself, dressing, opening doors, vacuuming, cooking, peeing, fixing hair, feeding pets, walking pets, carrying grocery bags, and laundry. You also do not picture the increase in work that baby brings. There is more of every chore, more washing, more washing of all household items and more washing of oneself. Actually less washing, if you're like me, but more washing of one's clothes and hands. Somehow this all adds up to a constant workout.

And then there's the other kicker: the baby grows like a weed into a solid 25-pound toddler that may not be walking yet. Now you are toting a real bag of rocks. Except that bag lunges away from you, that bag kicks you, that bag grabs things off shelves and pulls your hair and wiggles and crawls and twists and runs into the street. That bag is nearly impossible to hold on to. Your arms feel it first when baby gains weight, or your back. Because it takes a few weeks for your body to catch up, to gain a little more muscle. You've never had biceps like this. You know what it means, now, to throw your back out.

So it's a workout, this baby-toting. There are delightful upsides though. After six months of the new baby workout — aided by our laundry being two floors down and living one floor up from the street and doing a lot of our shopping by walking — my baby weight was gone and then some. I could not eat enough, though I definitely tried. I was never full. Even as your kids grow and the lifting lessens, you are still on the move because your kids are now exceedingly active. They are always going. Sometimes you lead, sometimes you follow. Sometimes you drag along behind.

I couldn't have known, but I am still surprised by how intensive the mom workout is. It's not a marathon because it happens every day. It's not a game or a sport because you didn't mentally and physically train for it. It's not even a workout because there is no recovery except sleep. All I can say is it's physical, and dream moms, you've been warned. Embrace the sweat.