For my birthday a few months ago, my husband got me a Fitbit. I’m ob­sessed with it.

A Fitbit is a small device you wear inside a band that goes around your wrist. It has magical powers and can tell when you’re walking or running, and it tracks your activity throughout the day. The goal is to take at least 10,000 steps every day.

Once you hit 10,000 steps, the Fitbit lights up and buzzes happily. When you sync your device to the Fitbit web site after hitting 10,000 steps, you’re rewarded with a big happy face with a cartoon-like speech balloon that says, “Hooray!”

“Hooray!” is only for 10,000-step winners. Not lazy, 9,999-step losers.

I got the Fitbit in April, and it recently sent me an e-mail alert that I’ve walked/run a total of 750 miles, which is the length of California. Score! Or as Sir Happy Face would tell me, “Hooray!”

Why am I able to walk this far? Partly because I like to run and exercise anyway. Partly because I have a child who doesn’t like to go to bed and requests that I go up and down the stairs many times between 8 p.m. and 10 p.m. because she “heard a sound that sounds like there’s a bird in the closet.”

There is never a bird in the closet. But at least I’m earning steps.

But I think the main reason I walk so far is because I simply cannot bear to not hit 10,000 steps by the end of the day. Just last night, I was about to climb into bed and saw my Fitbit was only showing 9,940 steps.

Oh, that wasn’t going to work.

I went downstairs and walked around and around the kitchen island until I got in my remaining 60 steps. We have a pretty small kitchen island, so I was dizzy, but satisfied. And I knew this was not rational behavior, but I didn’t really care.

And I wonder: Would I have this obsession with hitting the “right” number if it weren’t for myeloma?

Before my myeloma diagnosis, I was not a “numbers person.”

I suffered through four years of high school math and managed to graduate from college with just one algebra class. It’s not that I was necessarily “bad” at math; I usually understood most of it and got halfway decent grades. I just found it boring. I didn’t care about numbers.

I was an English major. I preferred words. Numbers are simply black and white, I thought. They carry no meaning or emotion.

At least that’s what I thought until my diagnosis. Then I found out how much emotion a simple number can have. With myeloma, one number can make me rejoice or cry or worry for a month straight.

You’d think that after nearly nine years of this, I’d be an old pro. You’d think I’d no longer worry about getting my test results. Not so. Every month when the nurse calls me with my results, I hold my breath while I wait for her to reveal the magic number.

My M-spike has been mostly stable for the past several years. Every now and then, it will creep up or down slightly. When it creeps down, I rejoice. I’m the big happy face shouting, “Hooray!”

When it creeps up, I’m shaky with fear, wondering if this is the beginning of a trend. All I can do is wait out the next four weeks, hoping it will go back down. I can’t just do laps around the kitchen island to make things better.

Maybe that’s why I like the Fitbit. I get to see numbers that affect my health, but I’m able to control them somewhat. I can take action to get them into the healthy range. With myeloma, there is no immediate control over the numbers.

For several years, when the nurse would call me with my test results, I would request that she’d mail a copy of everything to my home. A few days later, I’d sit down at the kitchen table with the complete set of results and study each and every number. Even though most of them would be within normal range, I would still look closely at everything, wondering why something had gone up 0.1 or down 0.2.

After a while, I stopped asking for the copy to be sent to me. Even though I’m a big believer in knowing all there is to know about my disease, I knew I needed to stop obsessing so much over each and every number. Now I simply ask the nurse to let me know if any numbers are out of the normal range, and I leave it at that.

I’m attempting to let go of the hold that the numbers have on me, but I know I’ll never have complete success with that. If you need me, I’ll be walking laps around my kitchen island.