...is physical fitness, IMO. We've had a lot of really good discussions here lately regarding self defense, mostly with a handgun. But the comments Thomas made here
http://nebraskafirearms.org/forum/index.php/topic,10008.40.html about defending against an aggressor 15 feet away with a baseball bat brings up a good point that a lot of people overlook. What happens when you can't use your gun? Are you going to be physically fit enough to survive the encounter? Even if you are able to successfully defend yourself with your handgun you very well could be injured in the exchange. Someone who is in good physical shape has a much better chance of surviving a traumatic injury than a couch potato.
Now, I will be the first to admit that you can't expect to be able to physically overpower every aggressor. The fact is, there is always someone bigger, stronger, and faster. And I know firsthand how it gets harder to stay in shape as we age. I'm still relatively young at 37 years old, but I can't run as fast as I used to and it takes longer to recover from physical activity than it did 20 years ago when I was a high school athlete (man, writing that made me feel old). That's why we carry a gun, so we're not at the mercy of those who are physically stronger. The advent of firearms is one of the technological advances that helped bring about the end of serfdom and ushered in modern Western civilization. As the saying goes, God made men, but Sam Colt made them equal.
But a handgun is not a magic wand. No matter how much you train, no matter how good you are, there's always the chance that you will be unable to use it for one reason or another. If you aren't paying attention to your physical health you are putting yourself at a serious disadvantage. Why not use all the tools you have available?
And with that said, I'd better go for that run I was planning on tonight so I don't look like a hypocrite