In my high school, all you needed to get a varsity letter in cross country was, I think, to get under 19 minutes on a 5K. Most of the varsity letter requirements for other sports were similarly easy to meet. Our school wasn't known for athletics.
My first race was a little under 22 minutes long, and every year I struggled to get my time lower than 19:50.
My senior year, I had hit puberty, so I had more strength and cardiovascular fitness than before. I figured I would make it this time, and I trained as optimally as I could. I followed the coaches' directions more closely (my brother and I were once told that, given our fitness, we should never run slower than 9 minutes a mile for an easy run; it took until senior year for me to actually follow that advice). I ate well, slept...probably poorly, and I felt pretty fit compared to previous years. My dad bought me and my brothers Garmin Forerunners, which are GPS watches that can tell you your pace in the middle of a race. He came to as many of our races as he could all throughout high school, and our mom did too (she came to our middle school races in addition to high school ones -- it was no fault of our dad's, not to come to our middle school races; I find it impressive and touching that he made it to almost all of my high school ones. In middle school it was always some random distance so we never really had a consistent distance to truly compete against ourselves with. High school had bigger teams and each race always right around five kilometers, with one notable exception).
The watches helped a lot. (I still have mine from back then, but it struggles to hold a charge for a full run unless you've kept it in the charger until the minute you go running. I don't use it quite as much; I've misplaced my charger too often, and I don't want to look for it a day in advance just so my watch can tell me my strides per minute (arguably important, but I digress). I can't pace myself any better than in high school, but I don't need to because there's no exact season or race I'm training for -- though for something big, like a marathon, I will actually use the watch. My phone can record my pace for less-important runs.)
Anyway. Back to the point. I hadn't broken 19 minutes my whole senior year, and we were down to one last race. I was anxious the whole last week. The last three days, I could practically feel adrenaline seeping into every capillary like I was a sponge. It felt good, unsurprisingly to me (though that may be surprising to you). I felt ready.
The last meet was big, full of schools. I'd just learned from my dad (either that day, or just before some other race in the past week or two) that the "strides," or short almost-sprints you do a few minutes before a race, are actually important -- they prime your body for that first 100-meter dash where you stake your position for the next mile. If you don't do your strides, you'll dip into anaerobic metabolism early, and your legs might be locked up halfway through the race, and that's bye-bye sub-19:00.
I felt like I weighed like nothing. My entire body was a spring. Side note: if you've never put on racing flats/spikes, I encourage you to borrow a pair for a short run (and I mean short! Like 100 meters if you don't run, and a mile or two if you do run). It feels like there's a weightless force field on your foot, with how light it is compared to a normal shoe. It's a surreal feeling.
When we started the race, I felt a touch desperate. I ran only a little slower than my best; you're supposed to hold yourself back for the first mile. I knew that, but I glanced at my watch to see that I was averaging a 5:00/mile pace. That was WAY beyond my target pace, and I barely even noticed. That was heartening to see, but I obviously dialed the pace way, way back to 5:45/mile or something. I needed this record-breaking adrenaline to last me for three miles, not half of one.
Frankly, all I remember of that race was that first 200-meter dash and the disconnect between what I felt and what I saw on my watch. I always have that disconnect during a race, but it was especially pronounced during this race.
The next two miles were hard but good, and I broke 19. I got a massive personal record (PR) to end my high school career with; I think it was more than a minute of improved time. Which is rather insane. Improvement tends to be more incremental than that, but things like this do happen pretty often in running, especially at the relatively slow paces I ran at.
My brother broke 19 and 18 in the same race. Just skipped right over the whole 18-minutes-something-seconds window. I was over the moon for him, of course. We'd both made it past the lettering-qualification by the skin of our teeth, and at the same time, by a huge margin.
He's kept up with consistent running more than I have. He's also gotten me back into running after I semi-gave up on it, and our older brother's gotten back into running too. We, along with our dad, decided to run a marathon/half-marathon together this summer. I'd say we all did well, though I didn't train as much for it as I should have.
I've only ran one marathon so far, and it was recent, but now I'm feeling the itch. I want to run another one, I want to absolutely demolish my time. Admittedly, this is partially because I didn't practice as much as I should have, and I've seen my brothers' times, so I know how much farther I can go.
If you've come close to your (previous) best at something, you might have realized too that it was only a false summit. Could be a project within your hobby, could be a physical accomplishment, it could be anything that requires some level of effort large or small. But I hope, when you realized you could do even better than you just did, that it felt inspiring.
It's kind of a rush.