The other day, as I started sliding my left arm into the shirt I had selected for the day, I felt a shooting pain in my shoulder.

That was odd, because my shoulder hadn’t been seeking attention prior to this. But there it was, barking at me and making it difficult to pull on my shirt.

I let it slide, thinking things would be better the following day.

They weren’t.

Same routine the next day. And the next.

I knew nothing was seriously wrong, other than inhabiting a body trending toward obsolescence. So why not break out of my routine: Why not slide my right arm into the shirt sleeve first?

So I did. Or, shall I say: So I tried? Because, almost unbelievably, I couldn’t do it; I could not get my right arm to slide into the shirt first. I kept fumbling with the fabric and twisting the shirt’s torso to give my right arm the correct slot, but I couldn’t make it happen smoothly.

Again, for a moment, I wondered what was wrong — surely, pulling on a shirt shouldn’t be this difficult.

And then it hit me: I’ve been pulling shirts on starting with my left arm for so many years, my brain and body just take over and don’t readily adapt to change.

So I decided to experiment: What happens if I start brushing my teeth on the upper right side of my mouth instead of the customary lower left?

Sadly, same result: The simple change confounded me. It felt odd brushing the right side first, so much so that I lost track of what I was doing. When it was time to shift to a different quadrant, I couldn’t smoothly complete the move. And then I couldn’t even finish because I was so discombobulated.

Out of curiosity, I tried tinkering with other normal daily activities: I realized I always begin washing my face with my left forehead, so I tried my left cheek first instead. Bad idea.

I step into the shower with my left foot first; I know this now because starting with my right foot made it somehow difficult to close the shower door since my body isn’t in the “right” position.

When I’m popping out of my car, I put my weight on my left foot first. I tried the right foot instead and almost jammed the door into the front fender as I fell off-kilter to the side.

Same with eating cereal, grabbing a glass of soda, peeling the paper from a straw, even dropping sweetener into iced tea: I do all of these little things exactly the same way, every time, without even knowing it.

Well, the good news is that the pain in my shoulder seems to be gone now, and I’ve returned to my comfortable left-sleeve-first route.

Yes, it’s a routine, something we’re typically not supposed to fall into if we want to live a happy life. But I can now say I gave it a shot and found out that maybe I need routine to stay happy.