I went running tonight. I didn’t know what else to do.

I’m not a marathoner. I doubt that I ever will be. I’m not disciplined enough, and I don’t want it badly enough. So I can’t tell you exactly what Boston means to those who run it, but I have a pretty good idea. If you’re a marathoner, that’s it – Boston. There are loads of other races, but Boston is The Big One. The oldest. The most prestigious. The race for which you other races in hopes of qualifying.

And I can tell you what the finish line is like because I’ve crossed the finish line of lots of other races, including last year’s Chicago Marathon, which I bandited in support of a dear friend. The energy at the finish line is tremendous, and runners count on it. It’s like a nitrous ‘go’ button on a souped up car. You come around the corner and you see that finish line and you hear the roar of strangers and friends and you’re just swept away. If you’re on the other side, waiting in the crowd, the finish line is electric with anticipation. Everyone is waiting to catch a glimpse of that special person who has labored for 3 miles or 3 hours, waiting to scream that person’s name with excitement and pride as they take the last few steps of this race they’ve trained so long to run.

Last week, a friend of a friend said something derisive about the distance I’m running in a race next week – the half marathon. His comment really got under my skin, and today as I ran around Humboldt Park in the rain, grieving for the injuries and losses suffered by complete strangers, I understood why.

Running – becoming a runner – changed my life. I’m not a fast runner, and I’m probably not a good runner, and I struggle to do it, and I struggle to stay motivated, but for the last five years, it has been an unambiguously positive part of my life. I have met the best people, and had the most amazing experiences because of running. I have pushed myself – my body, my heart, my mind – past the point of exhaustion, and, more importantly, past what I believed I was capable of doing.

99.9% of us enter races knowing we’re only competing against ourselves. There’s no prize money. There might be a medal, but everyone gets a medal. But that’s not the point. The point is that we did it. I feel as proud of the half marathon PR that I logged last April as I do of the first 5K I finished five years ago. I am as proud of my friend who is struggling to run a 12 minute mile as I am of my friends who ran the Chicago marathon last fall. And I will cheer as whole-heartedly at the finish line for the friend pushing for a PR as I will for the stranger whose name I can call out because it’s printed on their race tag.

These things are why Boston matters to me. These are the reasons I cried at my desk when I read the news, why I cried in the car, why I’ve been glued to the news coverage, why I couldn’t do anything except lace up and run in the rain. Because each of us run for our own reasons, but we’re out there together – in the rain, in the snow, in the heat, on the Lakefront path, sick, injured, overdressed, out of shape, on bad days and good. Because we exchange smiles or head nods. Because we stand on the sidelines and cheer for every runner whose name we can read. Because our friends and family do the same. Because we say ‘thank you’ to each and every volunteer who stands with rubber-gloved hand outstretched, offering a cup of water or Gatorade at mile 1 or 10 or 22.

Random and terrible acts of violence happen every day. More people were killed in Chicago last weekend than died at the marathon today. But while Chicago is closer to home, Boston is closer to my heart. Because those people at the finish line were there because they loved someone in the race. Or because they got up early on a Monday to help. Or because they’re passionate about running in general or this race in particular. Or because they finished the race and decided to watch while they stretched out overworked muscles. Or because they had just made that final push across the finish line four hours after starting. Because those people could be my loved ones, and those runners could be my friends or me.

So I laced up my shoes, and I strapped on my watch, and I went running in the rain – the park, two laps, then home. I smiled at every runner that I passed, and every single runner smiled back.