Lap 1 This is not so bad. Kinda funny actually. And historic, sorta. I’m running the Arena Attack, the first indoor marathon held in Massachusetts since 1928, when Little Joie Ray of Chicago beat El Ouafi, the reigning Olympic champion, in front of 7,000 people at Boston Garden, breaking the indoor marathon record in the process.

I’m not actually running the full marathon; I’m doing a half-marathon that starts at the same time, but I’m still going to pretend I’m a part of history because my brain has to rationalize the poor decision I’ve made.

Lap 2 Have I talked about the course? Well let me tell you about it, because after two laps I’m an expert. The entire race takes place on the concourse at the Mullins Center at UMass-Amherst, the arena that is home to the school’s hockey and basketball teams. You know that area where you run to the bathroom during a timeout? Maybe grab a burger at the concession stand? Yes, there. Just run around that 133 times counter-clockwise and you’ve completed the marathon.

Lap 5 I get lapped by the marathon leader, a guy from Elmira, N.Y., named Rob Toonkel. This is his 318th marathon and his 17th indoors. This is his third indoor marathon this month (the others were in Minnesota and Connecticut), and he will later tell me that he likes running indoors because you don’t have to worry about things like weather or hills or bathrooms, and you can just get right back to your car without needing a shuttle. But he also tells me that running indoors is much tougher mentally than running outdoors. By then, it will be like telling me that water is wet.

Lap 10 OK. This is not so bad. I’m about 2 miles in, feeling warmed up, and the concourse has floor-to-ceiling windows that allow in plenty of sunlight. I can do this.

Lap 18 So I’ve only got to do 66 and a half laps for a half marathon, but they started us halfway around, so I’ll cross the finish line 67 times, and I’ve done 18 and so, wait, how many laps do I have left?

Lap 21 There’s a spectator area, a couple dozen cushy red seats in a roped-off area. At most, there are 10 people there, and half of them are asleep. A few of them have pulled chairs together to lay down. The rest of them are staring at their phones.

Lap 30 I went to the bathroom. I didn’t really have to go. I just wanted to stop running and hide.

Lap 34 I think I’m halfway, but my ability to do simple math is long gone. And I withdraw my earlier statement about how I knew everything there was to know about the course after two laps. There’s so much to see if you bother to look! For instance, there are seven concession stands, including one that sells locally made ice cream. You can get five scoops, plus sprinkles, for $7, which sounds like a deal, and they have a “UMass Signature Flavor.’’ Based on my previous experiences at ZooMass, I’ll have to assume that’s Natural Light.

Lap 40 I have a new friend. I’ll later learn that her name is Alexandra Ly, and she’s part of the women’s ultimate Frisbee team at UMass. They’re the race volunteers. Some of her teammates are running the water and Gatorade station, and the rest are with Ly at the finish line, tracking the runners as they pass and yelling out what lap they’re on. (There’s also an electronic chip tied to our sneakers.) Ly is assigned to track me, and she becomes my coach, only fan, and chief math officer. She is the only thing that matters in my life. I just need to see her 27 more times; then I can ask her name, thank her for her help, and go throw up.

Lap 44 I’m two-thirds of the way done, right? I’m not sure. But that’s not what concerns me. No, I’m mad at the exits. Did they really need 14 exits? Is that not a bit excessive? Sure, if there were a fire and I was one of the 9,000-plus people that can fit inside for a basketball game, I’d be glad there were 14 exits on the concourse. But not now. No, those stupid orange EXIT signs are just taunting me every 75 feet. Stupid exits.

Lap 48 There are banners hung around the concourse, mostly of hockey and basketball players, but I notice one that is, I think, Trey Anastasio from the band Phish. I wouldn’t be the first person to think they’ve seen Trey Anastasio while they were hallucinating.

Lap 50 The windows are not to let sunlight in. No, they’re to let dark thoughts in. Look at those people out there enjoying this unseasonably warm Sunday in January. Those people have it all figured out, man. They have no idea how good they have it. I’d do poorly in prison.

Lap 54 Rob Toonkel passes me again. I’ve lost track of how many times he’s lapped me, but I always know it’s coming because he has the heaviest, clumpiest feet I’ve ever heard. I would hate to live below him. I’m sure the floor isn’t helping the noise either. Did I mention that we’re running on concrete covered in tile? Yes, because the ideal running surface is to take something incredibly hard and then make it slippery.

Lap 56 I’ve chosen an enemy. A woman, muscular, wearing a neon tank top. I wasn’t planning on having an enemy, but she passed me just as we were finishing a lap, and according to the spotters, she is one lap ahead of me. I vow to make up that lap and defeat her because I need some outlet for the hate and anger brewing inside of me.

Lap 64 I pass Alexandra Ly, and she holds up two fingers. I tell her I think she’s wrong, that I have three laps to go. She says no, only two. My emotions are fragile and I do not need this right now.

Lap 65 Two fingers again. She has checked her count against the computer and is apologizing profusely as I run past. I forgive her because I have made up enough ground that I can now see the neon shirt of my enemy in front of me, and I’m focusing my anger there.

Lap 66 Caught her. She does not seem to care.

Lap 67: I’m done. Oh, boy, am I done. My body feels much worse than it did after each of the two full marathons I’ve run. The concrete, plus the constant left turns, plus the math fatigue, have me questioning whether I can survive the drive home. My time is 2:00:14, putting me 11th out of the 20 people in my half-marathon. I’m tempted to say those were the worst two hours of my life, but the truth is I didn’t hate the first 20 minutes. As I’m walking to cool down, I see the 28 new people who are about to take off on the second half-marathon group of the day (basically joining the last half of the marathon), and, to my credit, I refrain from telling them to flee.

Lap 133 Rob Toonkel wins the marathon with a time of 3:46, more than an hour off the current indoor world record. It was, for him, a rather lackluster time, but there were only 10 men in the men’s marathon, so it worked. Sarah Bousquet, a high school teacher from South Hadley, won for the women in a time of 4:48. There were only two women in the marathon, but she may be the first-ever woman to win an indoor marathon in the state, so that’s cool. I did not get to meet her because by then I had found a UMass student I know and gotten him to swipe me into the cafeteria so I could attempt to set an indoor eating record.

Billy Baker can be reached at billybaker@globe.com. Follow him on Twitter @billy_baker.