I'm already dreading my New Years resolution, and it's still weeks away. Like millions of other Americans, I'm going to start working out—specifically, running. I love the way running makes me feel, but only when I'm not running. This is because even when I'm racking up modest mileage, my legs burn, my chest itches, and my lungs feel like they're filled with a thousand burning matches.

I want to be a runner, but even Bruce Springsteen's exercise anthem "Born to Run" can't get me excited. (What's that? The song is actually about teenage angst? Oh, maybe that's why.) I don't want these factors to derail my resolution. To find out why running feels so sucky (and hopefully make it suck less), I called Steven Magness, coach to several Olympians and the University of Houston cross country team, and author of the book The Science of Running.

The seven-step itch ——————-

I don't want to totally shock my system once January 1st comes around, so I'm going to prepare myself with short jogs before New Year's. I had my first this weekend, and as expected complaints flooded in from every part of my body. The first came from my skin. I hadn't made it to the end of my block before my chest started itching. It was like someone had stuffed my shirt full of wood chips. What's actually happening, says Magness, is blood flowing into tiny unused capillaries in my skin. In non-runners like me, these capillaries are dormant. When they get flooded with blood irregularly, they swell. This irritates nearby nerve endings, which sends itchy sensations to the brain.

Burning muscles —————

Not long after this, a familiar fire started burning inside my leg muscles. Magness assured me that even top runners feel the burn. It's caused by a buildup of lactic acid, but is really a signal your muscle is using to let your brain know it's running out of energy. "Pain is feedback for your brain to let you know how hard you're working," Magness said. Thing is, this pain signal typically comes well before your body is actually tired. Push through, and eventually the burn will simmer down, says Magness. Eventually, you'll build up enough endurance that your muscles won't freak out so soon.

Side stitches ————-

Not long after I pushed through the burning in my legs, I was assaulted by side cramps. Like a big, invisible hand had grabbed the side of my belly, I doubled over and immediately started walking with my hands on top of my head. The pain subsided, but left me wondering where it came from to begin with. For a while, says Magness, researchers thought was that side stitches would come from the body getting low on electrolytes like sodium and potassium. But, studies showed that electrolyte-depleted athletes are no more prone to side cramps as those drinking healthy amounts of Gatorade.

Currently, says Magness, there are two prevailing hypotheses. The first is that running causes you to strain a ligament connecting your diaphragm to the abdominal muscles. "When you're running, your diaphragm is working harder than you expect," Magness said. The second hypothesis is also tied to the abdominal muscles, but has to do with a decrease in calcium, which can prevent muscles from relaxing.

Gasping for air —————

Not long after my legs started burning, the fire spread to my lungs and I began gasping for air. This happens, says Magness, because our bodies aren't perfect at cycling CO2 out of our lungs. "You are breathing so intensely that you can't get all of the bad air out," Magness said. Even when you're breathing normally, there's never a perfect exchange of oxygen to carbon. With running, your muscles get so starved for air that they don't leave you time to exhale completely. Eventually you build up such a huge deficit that you get a burning sensation similar to holding your breath. "At this point, you stop, and bend over, and suck in, and you can finally catch up," Magness said.

"Bubbleguts" ————

I had planned a two-mile run, to the top of a hilltop park. There, I'd catch my breath while looking at beautiful San Francisco, then return. I didn't make it so far because my tummy started burbling before I was close to the first sloping street. I ended up speed walking the last few blocks home. "This is pretty common," Magness graciously told me. Many runners also get gassy because their bodies are breaking down energy (in the form of sugary carbohydrates, solid proteins, or rich fats), causing muscles cells to release gas. A lot of this gas ends up not making it to the lungs, where it can be expired without embarrassment. As Magness tactfully put it: "Gas gets stuck in places where it shouldn't be, and you gotta get it out some way." Also, he says, the mechanical jarring of running helps along the digestion process.

Magness says these problems are most common with beginning runners, but even the Olympians he coaches admit to suffering. So maybe I wasn't born to run, but at least I know I'm not alone in my misery. Maybe one day I can catch up to the pros, and take my complaining to a whole new level.