So you've decided to start running. First off, congratulations are in order! Maybe a friend convinced you to train for a marathon with them; maybe it was your New Year's resolution and you own a wildly inaccurate calendar, but one thing's for sure: This will be a beautiful and disgusting journey for you. The reason is that, while healthy for you, distance running will cause your body to get very mad at you, and rebel against you in all sorts of horrifying and gross ways. Ways, such as:
1. Your Body Will Fall Apart
Running can lower your blood pressure, decrease your risk of heart failure, and improve your day-to-day alertness. Hopefully that will be some nice consolation while you are icing approximately your entire body with some kind of wraparound ice pack after your muscles decided they were done doing it. Whether just getting started, or a long-time distance runner, running can cause one of any 100 or so injuries. Did you run too fast when your feet were twinging? You could get plantar fasciitis, which means you've disconnected the muscle in your foot from the bone. Go running in flip flops and now your shins hurt? You guessed it, your muscles started to tear away from your shins. Almost invariably, running injuries involve your muscles desperately trying to escape from your skeleton, presumably for daring to exercise. Fortunately, slowly working your way up can mitigate them, but one way or another, you'll eventually get hurt, and at that point there's nothing to do but take a break for a while and rest.
2. You Will Have Night Cramps
So you've gone for a run, spent the rest of the day not running, and now it's time to go to bed. Your body can't hurt you in your sleep, right? Wrong! You will find this out if you ever wake up to the feeling of your calf tying itself into the tightest knot imaginable. Running makes you sweat, and that sweat contains precious electrolytes, so if you don't drink a sports drink or eat a banana, your muscles are liable to go all Rambo on the sheriff of this here town, i.e. you. So, there's that to look forward to. Now, about that sweating...
3. You Will Sweat For Hours For No Reason
Sweating is your body's way of cooling down, and when you start running, your body gets in the habit of needing to cool down a lot, for long periods of time. As a result, your body, trying to earn a gold star for initiative, will start taking any amount of exercise as an excuse to start sweating as if you were running a marathon. Run a quarter block to catch the bus? I hope you're ready for a full 15 minutes of straight-up Olympic sweats as you try and find a seat where no one can stare at you. Of course, this is the tame side of sweat. When you're actually running, sweating can do much, much worse.
4. You Will Chafe Until Your Nipples Bleed
Please do not quit running, this will only happen if you run really far. Like, say, a marathon. When you run, your shirt becomes like paper, and the salt in your sweat becomes like grain, and the two combine to form, basically, sandpaper. So over the course of a marathon, don't be surprised if your skin gets raw, and yes, your nipples bleed. I'll save you the agony of looking, but if you are not at work, and are very far away from anyone who can judge you, a brief Google image search of the phrase "Marathon Nipples" will give you a solid idea of what happens, and then maybe make you throw up.
5. Your Toenails Will Die
You can think of running as a war against standing still, and your toenails as some business-minding civilians who just wound up caught in the crossfire. The hard ground pounding, repetitive motion of running can cause any number of horrible toenail injuries, ranging from bruising, (sure) to under-nail blood blisters, (bad) to your toenails just straight-up falling off, (terrible). This might not seem like a disaster, but it's such a frequent annoyance that many ultramarathoners have their toenails surgically removed so they don't have to handle the hassle. Again, that is the hassle of having toenails.
6. Yes, You Very Possibly Might Shit Yourself
This actually might be a good thing, because for a sport without points, shitting yourself in front of 40,000 people at the Boston Marathon is the closest thing running has to an own-goal. Running draws blood to your legs, and, blood having to come from somewhere, it is taken from your digestive system. Mix the compromised gut with intense sweating and constant bouncing, and you will almost inevitably find yourself in a desperate race to the bathroom, or, who knows, maybe in a much worse situation. Again, yes it happens a lot, and again, please do not Google it at work.
So get out there, slugger! The sooner you start running, the sooner you'll be too tired to think about this stuff.