I have never felt older than when I saw Ed Sheeran live in concert. I had discovered Sheeran's music through a TV show and while I assumed that show's audience skewed a bit younger (it was 'The Vampire Diaries', OK?! Get off my back!), I was shocked when I arrived at Madison Square Garden in November of 2013 and was surrounded by teenage girls. Still, that wasn't so bad. I was glad that his duet with Taylor Swift, "Everything has Changed," from her 2012 pop masterpiece, 'Red', had introduced such a talented artist to a wider audience. Swift herself even made a special appearance to sing the song with him. It was great.

Not so great was the moment that came shortly before that, when Sheeran covered Nina Simone's "Be My Husband." As a longtime Simone fan, I cheered–loudly–when he mentioned the chanteuse, but my excitement quickly turned to embarrassment when I realized that I was the only person in the entirety of Madison Square Garden who had made a sound. Sheeran's voice quickly covered the low mutterings of the young girls around me, but they're confused, frankly the little judgmental stares had a profound effect. For the first time, at age 25, I understood what it was like to be in a space I was clearly too old to be in.

Since then, I've been somewhat wary of attending the concerts of artists whose audience I know skews early 20's or younger. I see roughly a half dozen concerts a year—most of them alone. While the near fist fight I got into at Terminal 5 last year is the only bad thing that's ever happened to me during a show, there is something profoundly isolating about attending a concert with a bunch of young girls. There is a cliquishness about these groups of small, screaming girls that feels reminiscent of the kinds of high school lunch rooms you always see in movies. You feel like someone's going to call the cops on you when you're the oldest person in a room full of young girls who isn't a parent or chaperone. So, when Shawn Mendes (you know, the cute kid who sings that "Stitches" song that was everywhere last year) announced he would preview his upcoming album, 'Illuminate' (out September 23), at MSG, I hesitated. However, based almost entirely on the quality of his single, "Ruin," which sounds like a lost John Mayer track, I bought a ticket. And I am so happy I did.

I have not loved 2016. A few of my friends have been very ill and my job has to do with the US election cycle, so I'm sure I don't need to explain why that's been stressful. So, I went into MSG this past Saturday feeling a bit run down. All I wanted was to hear a little live music and not have to stand the whole time while doing it. While I got exactly what I wanted, I also got something even better: the restorative, boundless energy of the girls in the audience. I don't want to fetishize young women (God knows there's enough of that in this culture), but watching Mendes's young fans experience that concert was just about as enjoyable as the music itself.

I've been getting dragged going to concerts since I was a toddler, but I can't recall a more excited audience. These girls were ready to sing their hearts out even before we got into the arena. As they shuffled slowly out of the suffocating humidity and into the cool, echoing halls of MSG, they sang the lyrics to one of Mendes's other new singles, "Treat You Better," as it played over the speakers. They yelled every time they hit the phrase, "better than he can," at the end of the chorus and laughed as they did. Once inside, the arena was practically buzzing with their excitement as groups of girls flitted between their seats, the snack bars, and the especially crowded merchandise kiosks. A less generous observer might have found it obnoxious, might have criticized all the Snapchatting and self-conscious primping, but there was something thrilling in realizing how new and exciting this whole process was to so many of these girls.

Take the group of middle schoolers who I helped find MSG before the show started. This was the third concert one of them had ever been to. I couldn't even tell you how many concerts I've seen in my life and it was so refreshing to hear how proud that girl was of that number, how much the experience still awed her. Or take the teenage girls behind me in line to buy t-shirts. There they were, 20 mins after the time printed on the tickets and they were worried they were going to miss the whole show. Granted, there wasn't an opening act, but clearly, they hadn't been to many shows if they thought there was a possibility the show might start within the first half hour after doors opened, not to mention on time. Or how about the collective thrill that went through the arena when the uncensored version of Zayn Malik's "Pillowtalk" played pre-show. They were positively scandalized.

And then there was the concert itself.

The girls were almost rabid by the time the show finally started. I honestly thought they might start storming the stage as they chanted, "We want Shawn," over and over and over again and the collective roar of excitement when he finally took the stage was nearly deafening. While their energy flagged a bit during the middle of the show when Mendes played a number of new songs from 'Illuminate', there were many moments throughout when they sang so loudly that we couldn't even hear him. Their energy was boundless. I mean, there was a pre-show wave that made more revolutions around the arena than I've ever seen at an event—concert or otherwise.

Again, some might have found that energy exhausting, but I found it galvanizing, almost moving. Those girls were there to experience music they loved with people who felt exactly the same. That's not always the case at concerts. Sometimes I wonder why people show up at all if all they're going to do is drink and talk through the whole show. Certainly, there are cheaper, less distracting places to do that. Seeing a concert in a room full of adults can be so tiresome. It can turn into such a scene, a place for people to see and be seen while an artist they vaguely like toils in the background, the obligatory Instagram post as much about wanting to show off as remember a unique moment. Though there was a fair amount of phone action in MSG the other night–these were those dreaded Millennials after all–many of the girls used their phones' built-in flashlights almost exclusively as modern day lighters. Even when they did take a moment to record a video or take a picture, they screamed along to every lyric, fully engaged in the music and Mendes's performance in a way I rarely see.

To put it simply, being surrounded by all that uninhibited optimism and passion is incredible, humbling, energizing, so many things. And yes, there are inevitably some low points. Like the quartet of jaded New Jersey teenagers who made fun of me and everyone else in view in not-so-low voices before the show started. Yet even they aren't anything to get upset over. They're teenagers, after all. Being jaded and critical is what teenagers do. You can't begrudge them that because, sadly, one day they too will appreciate how wonderful and rare it is to experience that kind of pure, uncomplicated joy.