I've attributed it to a couple things, but I would love it is was something that was fixable. I personally think my problems are:
1) All my runs end up having lots of elevation, jut because i live in hills. I feel like that forces me on my toes more often. Not sure I can fix this, other than driving to other places.
2) I only run once a week, so it beats me up more than if I ran every day (I do exercise about 1-2 hours a day, but usually on a bike). Running more regularly seems like something I can fix.
3) Whenever I run, I run hard. Usually only 3 to 5 miles, but I try to hit it as hard as I can. Slowing down seems like something I can fix, but it also seems counterproductive for my goals.
4) My shoes are terrible. I hope that is part of the problem, as that's fixable. Any ideas on what kind of shoes might better help me out?

I wish I could run more often, but in terms of soreness, I get way more soreness from a hard 20 minute run (e.g., 7 minute mile pace) as I do from a hard 100 mile road ride (e.g., 20 mph pace). It really makes me not want to run.