When my mom turned 40, I decorated the house with cardboard gravestones, adult diapers and all the geriatric accouterment I could muster. Apparently, 12-year-old me thought 40 was ancient. Also, 12-year-old me was a bit of a dick about it.

Now, here I am with kids of my own celebrating surviving four decades of misadventures—and feeling anything but ancient. Sure, I take longer to heal these days and get a hangover just looking at cheap swill, but I've checked off more bucket-list items and tackled more fears head on over the past few years than I ever did in my early 20s.

During my 39th lap around the sun, I pocketed away some big rides, entered (and lost) my first trials competition, and entered (and won) my first downhill race. To celebrate my 40th birthday, I decided to check one more item off my list. With 13 tons of dirt sitting in my driveway, I begged friends to help rebuild the dilapidated pumptrack in my backyard under the guise of a rather unconventional birthday party.

Explaining this idea to non-riders resulted in the same question: "So, you're asking people to come over and do yard work? For your birthday?"

"Pretty much."

We assign birthdays the same empty grandeur that compels us to drive in circles waiting to photograph our odometer as it clicks over to 100,000 miles (or 80,085 miles as it were). It doesn't take long to learn that the passing of one day to the next doesn't really change anything, but line all those days up and you get the dash between our birth and death dates.

It's not until we're confronted with a tangible artifice of time's passage that we stop to absorb it. For some, it's the emergence of gray hair or flipping through photos from when that old hound dog was a rambunctious pup. For me, it came while looking over the indecipherable mounds and berms in my backyard that once acted as the Pied Piper of good times.

Nearly a decade ago, a friend who made his living building pumptracks turned a pipe dream into reality over a weekend. I was pregnant with my first son as I watched the mini-excavator tear into my yard. It would be months before I christened the new dirt track with my own tires, and I questioned whether having a fully built pumptrack and a half-assembled crib was the right way to prioritize—but it seemed right enough.

My newborn son sat cradled nearby when I took my first ride. Years later, he'd push dump trucks around the track with his little brother and sit on the toptube of my BMX bike as I spun slow laps while he giggled. Warm Friday nights became the universal cue for neighbors to pour over the fence.

In those flickering moments from the past, I can see small bikes scattered across the yard on the last day of school and hear my neighbor squealing with equal parts fear and excitement as her mom insisted on giving the "strange little bike track" a try. Some memories are backed by a laugh track of my own creation, while others are ensconced in silence but for a whirring hub that played its song until I'd expunged everything from seething anger to restless energy from my body.

As life hit rough spots, so did the pumptrack. Wear and wind slowly shrank its once-prominent features while grass overtook formerly impenetrable mounds of clay. For a while it seemed like moving from this little house was imminent. To prepare myself, I packed away any remaining aspiration of bringing the old track back. After all, what was the point? That chapter was closed.

But life changes quickly, for better and worse.

The future will always be filled with question marks, but for now, my grip on the reins is as tight as it'll ever be. I wanted my pumptrack back, even if it meant anxiously waiting to see if people really would come over for glorified yard work in the name of bringing back a piece of my past.

As friends arrived with gloves and shovels in tow, the pile of clay in my driveway shrank one wheelbarrow at a time. Blisters erupted from hard-worked hands that continued to wrap themselves around wooden handles until berms and rollers emerged from the ground.

Grasping my old Pulaski for the first time in years felt like going home. The weight of its axe head disappeared as it hung in the air during the fleeting moment between being thrust upward and coming back down with enough momentum to carve into the hardened earth. The rhythmic swings of my dirt scythe peeled away strips of rust-colored clay from a decade ago, leaving behind striated ribbons of clay like a snake shedding its skin in preparation for the next chapter.

By Saturday night, the moment of truth had come. After wrestling with berm diameters and insufferable flat spots that kept wanting to be flat, we began laying down first tracks to discover what worked—and what didn't. There in the dark, long shadows cast by a flickering porch light, I could finally breathe. There was plenty of work to do, but I knew for the first time that the track was going to ride better than ever before.

When I walked outside early Sunday morning, a loud voice boomed from the neighbor kid whose fingers were laced around the fence.

"Can I come work on the pumptrack?" he shouted. Apparently, he'd been waiting since sunrise.

As we filled the first wheelbarrow of the day, another neighborhood kid came over to help, joined shortly after by a sister and brother from down the street. My oldest son ran the Sawzall while my youngest shouted, "Where are my hoes?" I chuckled to myself, because even at 40, I'm still 12.

In the quiet of morning, my underage work crew earned their turns while adults were still home brewing their first cups of coffee. I couldn't ignore my aching shoulders and stiff back, or the realization that if there's a fountain of youth, it's probably made of dirt.