When people find out that I run, or have recently been for a run, they invariably want to know what I am training for. Actually I don't generally do "running events". I have done three in the last 7 years, I admit I did 'train' for one of them. One was "fun". One got cancelled.
So I usually say "nothing" or "to stave off death". Each of those answers is only half true.
Why else do I run? Why else should you run?
Run to lose weight. When I started running I weighed 130 kilograms. A hundred and thirty! I hadn't run a mile in about 8 years. I had a dream that I was running to a basketball trial for a national squad and I didn't make it. The ending of the dream was... ominous. I ran home from work the following day. At the time I lived 5 km from my office and I couldn't run halfway home. It's been a few years and I've been up and down the scale but I now weigh (a little) less than 100kg. I'm not going to get selected for the national basketball squad but I could probably run with them.
Run to get high. It really works but you have to work for it. But fuck - nobody is addicted to anything they didn't work for. I've seen people nurture their addiction to nicotine, alcohol, heroin... There is always a pain barrier (or a puke barrier, or a massively complex social network barrier, or some combination of all of them). If you don't get through it, run further. If you're a beginner I pick you'll need to break 6-7km to get your first hit. And then we'll jack up the price. If it is too mild and doesn't seem worth the effort, run up hills: big ones, the steeper the better. I used to run up the MTB trails from Logan Park High School to the top of Mount Cargill - when I got to the top and stopped the world kept moving for a few minutes. Trip-py. If you like that, find a big flight of stairs and use them: I recommend 6-10 reps of 6 flights of stairs in the middle of a 40 minute run (for beginners). 20 minutes out, 20 on the stairs, 20 back. You'll feel a bit sore the following day: jog it out for 5-6km. The next two days you'll struggle even to walk. But after that you'll want to go again. And it won't hurt as much: you'll have to go faster and hit the stairs harder just to maintain.
Run for pain relief. I have a slipped disc in my c7 and have been in perpetual pain for 6 months. I have restricted mobility in my neck and partial paralysis of my left arm shoulder and chest. I was on 100-150mg tramadols for nearly a month and they didn't touch it. They did make me partially psychotic though (swings and roundabouts, that's a whole 'nother blog post). But when I am running (and for a while after) I am whole again.
Run as perpetual training for a future reckoning with a long lost childhood friend. I used to imagine my best friend was there pacing me. One day we were going to play basketball or go mountain biking or running together again, and I had to be ready. He died. So for a while I ran to get back at him. Now I just let him pace me again.
Run to save the planet. More than half of my regular runs are commutes. Maybe I am not burning calories as efficiently as the train, or even a car, and maybe my shoes are manufactured by little slave kids, and the water in the shower I take after is heated by electricity generated by burning coal and on and on... but fuck it if those urban-attention-seeking cyclists can get press for taking a car off the road then I want a carbon offset.
Run to think. When you are running at a decent pace for a decent distance you (and anyone you happen to be running with) actually have to shut up for a while and... just think.
Run to heal an injury. I am not a doctor, but - except in cases of *serious* bio-mechanical disruption - your body will actually grow stronger the harder you make it work. "I get sore knees/feet/thighs/shin splints". Yup - so does _every_ runner. You injure a tissue and it grows back. It's how weight training makes body builders bigger. Running damages the connective tissues and contact surfaces in your body and (provided you don't blow them completely to bits) they grow back stronger. Find the balance - do enough damage that it has to grow back.
Run to find the hard questions to ask yourself. If you come up with any - let me know.