Originally, I only made the mp3 a minute long, and put it on loop. After about 30 minutes of this, I started to pick out the pattern of pops and hisses in the repetition, and then I couldn’t concentrate or think about anything else.

It’s Sunday before noon, and the gym isn’t dead, but not as busy as it gets when mom drags me down there on a weekday evening. Which isn’t often, thank god. Mom’s fit enough, and I suspect she only goes to the gym when she’s about to have sex with dad, or maybe right after. There are more women than men here today, which I’m guessing is because football is on but this gym doesn’t have any of the games on the TVs. I recognize most of the women. You’d think mom would come here with them, but then she’s probably not regular enough to have a standing gym date.

I’m not what you’d call a fast runner. I’ve got the treadmill on a comfortable warm-up pace of 6.7 miles per hour, which I’ll stay at for a few miles. Over on the elliptical, Mrs. Kensington is rocking out to something on her Zune. She keeps looking over at me and smiling. Last time we were here, she and I talked for a while, about school, the gym, the weather. I could smell her Degree antiperspirant fighting with fake Chanel and the tang of her own sweat. Not a bad odor, just not one you’d probably be glad to know people could smell. She touched my arm more or less constantly as we talked, wiping sweat away from her forehead with the back of her other hand. She said we should go running together sometime, since she’s scared to run alone “when my husband is out of town, like next week.”

Mom floats by, from the exercise bikes to the weight machines. I’m the only one on the treadmills, unless you count the Latina girl cleaning them. She’s wearing jeans and a heavy blue sweatshirt, her hair pulled back into a pony tail, not the slightest bit of makeup on her face, bright yellow rubber gloves on her hands. She’s squatting down with one leg on a treadmill, one leg off, cleaning the back of the support posts with a dirty rag. I can see the stitches in the crotch of her jeans shifting slightly as she rocks back and forth with the motion of her cleaning. I put my speed up to 7.1 mph and raise the incline a few degrees.

Talk to other guys, and they’ll tell you Mrs. Kensington is a milf, and even her son Kenny is only mildly embarrassed by this. I think he’s a little bit proud, too. Right now she’s wearing an actual leotard with thick gold-speckled tights, leg warmers, and a bandana. Her curly hair is piled on top of her head, her face is shiny, her lip gloss shinier, and there’s almost a perfect circle of sweat on top of her fake tits. We asked Kenny once, when did your mom get the fake tits? His answer, how the fuck should I know, more or less confirmed that they were indeed fake.

I think about what it might be like to motorboat those tits, but then my hand brushes the wheel on my iPod and I accidentally turn the volume up too high. I quickly grab it and turn the volume down again before my ears bleed, and the sudden movement catches the eye of the Latina girl. She looks up, looks at me, and goes back to her cleaning, never changing her expression, as if I’m as invisible to her as she assumes she’s invisible to me.

I push the speed to 7.3. I’ve never seen this girl here before, don’t know if I’ll see her again. She moves closer to the next treadmill, crouched over, and I can see a thin line of skin when the back of her sweatshirt rides up. Against the blue of her top and her jeans her skin is almost orange. I imagine that, with her sweatshirt off, and her jeans, she’s got small breasts with large brown nipples, and maybe just a handspan of belly sitting above her stark white panties. She’ll lie there while I brush my finger over her legs, soft, her pussy, plumped up between her thighs. Her stomach is warm, and when I bite her neck, her nipples become instantly hard in my fingers.

Mrs. Klieger walks by, touches the front of my treadmill, and actually gives me a wink. Mrs. Klieger has no kids, and while she may be, at 45, more or less fuckable, I’d probably have to be pretty drunk before I’d go down on her. I’ve seen 45 year old snatch on the internet, and let’s face it, you always wonder if their cigarette-scarred voices are going to coo at the wrong tonal range and ruin your hard-on. She’s wearing a tank top and short-shorts. Mrs. Klieger, according to the literature, is a Couger.

The Latina girl is only a few treadmills away now. I’m running at 7.7 (I don’t remember increasing the speed) and I’ve notched the incline up a few more levels. The white noise is drowning out even the sound of my feet slapping on the treadmill, but I can feel my heart pounding in my ears. I glance over at mom, who’s still working her upper body, so we have at least another 30 minutes before she’s done which is fine by me. If for some reason I can’t run for more than an hour, I usually have to go a lot faster, just to feel like I’ve accomplished something.

The Latina girl’s got one hand on a treadmill support, the other working the rag into a crevice, her upper lip curled in something like familiar disgust. At first, kissing her neck and working her nipples, she’s docile but willing, one had trapped beneath me while the other is slowly tracing a line down her body from her breasts, along her stomach, her hip and her upper thigh. But when I reach down to work my fingers beneath her underwear her eyes open wide. She’s wet, and when she pushes me off her to sit up and pull her panties down, I can smell how wet she is.

I put the treadmill at 8.5 miles per hour. I can run faster than this, a lot faster, but these machines top out at nine miles per hour, and I want to make the buildup last. Sweat is pouring down my face, and I glance up at Mrs. Kensington, her tits are bouncing to the rhythm of her elliptical, and she raises one eyebrow and smirks. Did she see me looking at the Latina girl? No, the staff are indeed invisible to her. My cock as flaccid, cold, tucked between my thighs with the motions of running. I’m wearing tight spandex running briefs, which have molded perfectly to my hips, ass, and thighs. One day, after a run, Helen saw me in those briefs and said I looked like a ken doll. I think she meant it as a compliment.

There’s probably a word for girls who are docile and gentle until you get their panties off, and then go crazy, gobbling your cock with those almost-frustrated grunts, and then all but shoving it deep inside them, willing you to ride them harder, deeper, harder, deeper, damn it. The treadmill is at nine miles per hour, the maximum, and I’ve put the incline all the way down again so that I can pump my arms, bob my head slightly, the rhythm of running smoothing into a glide. How about tigers, we’ll call them tigers, the Latina girl is a tiger, Mom’s moved over to the calf machines, Mrs. Kensington the milf is biting her bottom lip on the elliptical, the Latina tiger is standing on the treadmill next to me wiping down the display console as she works her hips and matches me thrust for thrust, her eyes rolled back, while Mrs Klieger the cougar gets up from her machine and bends over in front of me, stretching her thighs and putting her wide generous ass on display.

The clock on my treadmill pops, registering 59 minutes, 59 seconds completed and automatically dials back the speed for cooldown mode. The Latina girl glances at me again, makes eye contact, her expression still blank. She smells like baby shampoo and ammonia, and she removes her rubber gloves as she steps off the treadmill and walks away. I watch her ass but I can make out almost no definition in the back of her jeans. I turn on the small fan and almost shiver from the sweat evaporating off my shoulders. Mrs. Kensignton smiles at me one more time, an almost sad smile this time, and steps of her elliptical, walking to the locker rooms. Mrs. Klieger is over by the front desk, talking to one of the personal trainers. Mom’s in the stretching area, on one legs, her other leg bent behind her, holding her ankle and stretching her quadriceps.

I step off the treadmill and start my own stretches. I learned a long time ago that not stretching your calves after a hard run is pretty much the worst thing you can do. I dial down the sound of the white noise, and use the beat of the music playing out of the gym speakers to count out each stretch.

When I’m done, I drink water at the fountain until mom joins me. I ask her how he workout was. She shrugs. More or less the same as usual. I tell her mine was too.