The last day of school, I cried a lot more than I had expected. I said goodbye to the place that I had called home for six years.

I’ve come to believe that nothing truly prepares you for motherhood. When I was pregnant, people would ask, “So are you ready?” After hearing this over and over, my standard response became, “Well, we have everything we need, if that makes us ready!”

The truth is, I wasn’t sure. Of course I was prepared to physically take care of and "house" the baby. We had everything that we needed, and then some. We had the books, the support from our families, a fantastic doctor and a beautiful nursery. Despite all of that, in the back of my mind was a tiny voice that questioned if we were, in fact, ready to be parents.

I have to admit, my husband and I surprised ourselves. We had a high-needs baby, and took on every challenge head on. We managed to get through the excruciating first few months with flying colors, and now proudly have a happy, easygoing daughter. I wasn’t expecting it to be so hard in the beginning, but we did whatever it took, and whatever that was, seemed to work.

What I wasn’t ready for was how I would feel once things settled down.

When I found out I was pregnant, it was pretty much decided that I wouldn’t be returning to work. As a teacher, it financially made sense for me to stay home, rather than pay for decent childcare. The last day of school, I cried a lot more than I had expected. I said goodbye to the place that I had called home for six years—the place that helped me establish who I am as an adult. The place that took a chance of a first time teacher, fresh out of college. In my time there, I created fond friendships with people who would’ve never crossed my path under different circumstances, and I became more confident in myself both personally and professionally. I was leaving a work family to start my own family. I was both excited and nervous. I was going to be a stay-at-home mom.

Although I was sad to leave work, I was starting a new chapter in my life. I was looking forward to play dates, mommy and me classes, and the flexibility (should I emphasize the “first time mom” thing here?) that came with being a stay-at-home mom.

What I didn’t expect was to miss that old chapter as much as I do. Don’t get me wrong; I love being with my baby. I love taking her to music class, playing at the park on a nice day, and I love watching her learn to interact with her “friends” at our play dates. I know that my job as a mother is by far the most important work I will do in my lifetime.

But at the end of the day, something feels off. I don’t feel fulfilled, and that makes me feel guilty as a parent. It’s a vicious cycle. There are millions of women out there who would love to stay at home with their children, and I am choosing to return to work. But I can’t change how I am programmed. I feel as though there is a piece of my life that is missing. I feel as though I have started to lose myself. I feel as though I’m slipping so far from who I was, that I might not be able to get back.

And, in short, I feel as though I’m slowly losing my sanity.

That’s why I am choosing to go back to work, or to “lean in,” as Sheryl Sandberg says.

I am leaning in for my sanity.

I am leaning in to find myself again.

I am leaning in because in order to be the best mom to my baby girl I can be, I need to be happy, content, and feel fulfilled in my life.