It's gotta be the shoes.

Some people who know that I run often ask me about running shoes. How much should they pay? How should they feel? What to look for?
I always refer them to a running store, like Luke's Locker, and tell them to get fitted by a professional. I always say that things will be easier if they get a “real” running shoe, because it will prevent injuries and make the running experience more enjoyable.
But, an interesting post at the Science of Sport, a running blog that I absolutely respect, says the training, not the shoes, has the biggest effect on running injuries.
When I started running four years ago, I was pounding the pavement in some old Asics that I used to mow the lawn. After about three months, my knees were killing me. Was it the shoes? Or was it the fact that I was doing something my body wasn't used to?
Who knows. I eventually went to Run On, a running shop in the Dallas area, and they fitted me with some Brooks Beasts. This is a shoe for heavy runners who overpronate. But they were perfect for me at the time. (I wasn't heavy, but I overpronated). I eventually started wearing the Brooks GTS Adrenaline models. And have run both my marathons in them.
The only thing I don't like about the Brooks Adrenalines is that they don't last very long. After 300 miles, they are shot. I'm running in Asics now and am nearing 300 miles in a pair I bought at the beginning of the year. They seem to be holding up fine.
Looking for a scouting report on shoes? Here are the ones I've worn since I began running four years ago and a one-sentence comment. You can always go to Runner's World, which does a very good job of ranking shoes.
Brooks Beast: Good for me when I first started running long slow miles, but way too stiff and bulky.
Brooks GTS5: Favorite shoe. I did most of the training for my first marathon in these and never had one injury.
Brooks GTS6: A little narrower than the GTS5s and gave me bad blisters. But I started wearing 2Es and the shoe felt fine.
Asics Gel Empire: I ran my fastest 5K in these (21:09) so they have to count for something. But I always got the weirdest quad cramps.
Saucony Omni Moderate: These shoes gave me terrible shin splints. I even got shin splints when I walked in these shoes at work.
Saucony Hurricane: Felt like I was running in high heels and always had hamstring problems.
New Balance 767: Stiff shoe.
Brooks GTS7: Just like the GTS6s _ the wider shoe fit my foot well, but they wore out fast. I did most of my training for my second marathon in these shoes and they seemed to wear out the padding on the bottom of my feet.
Asics GT-2130: These are the shoes I'm wearing now. No complaints so far.
Feel free to take my running shoes survey at the top of the page.