I generally have a pretty good diet. I haven't had fast food in years, most of what I eat is lean proteins and fresh veggies; I limit processed foods and sugar, etc. A lot of this is because of ballet and over the years I've sort of developed eating habits that form my pre-season/season/off-season diets, preferred pre-performance foods, etc. It works pretty well at keeping my weight reasonable and fueling what I need to do in the studio and on stage.
When I did other physical activities, such as martial arts and weightlifting, I didn't really change my diet all that much and it worked out fine. However now that I'm learning parkour, I'm finding my diet isn't working, and I think it's because of the running, which I never really did before now. There was a year or two in college where I ran daily for 20 minutes or so, but back then I was taking a (bitter) break from dance and, you know, it was college so I mostly ate pizza and drank beer, the benefit of a youthful metabolism on my side.

That was years ago and I have since gotten back into ballet very seriously and have not run in a long, long time. I picked it up again when I started parkour, but now I have a *very* hard time with running, as many of you know. I can barely complete a mile, and I have very low motivation some days to "just do it" even though I know I should. Yet I know I *can* do it because in college I ran all over the place, every day, even in ice and snow, for extended periods of time. Most of the time when I think of running I sort of go, "ugh" and when I force myself to do it, it often feels really hard for me, like I'm running through mud or something. My body is just a big obstinate whiny wuss the whole time, like it's fighting me (the image I get is a dog being pulled by its master, digging in its paws because it doesn't want to go to the vet).
Anyway, sometimes, usually at times when I can't run (because I'm, say, in the car on my way somewhere), I get this urge to run. I feel like I could run and run for days, and I really want to. I don't know why this feeling never seems to come on right before I run, but c'est la vie. It occurred to me diet might have something to do with it, so I did some research.
Most of what I read talked about the need for carbs for runners. The recommendation I got was that a runner's diet should be 50% carbs. I eat very little in the way of carbs. Should I be eating more? Could part of the reason I feel I don't have the energy to run be from the fact that I eat almost no carbs (except for vegetables)? The last few times I got the feeling I really could run, and wanted to, I had eaten a meal with more carbs in it than usual (e.g. sushi, which is my favorite pre-performance food, precisely because of the carbs and protein; or a softshell taco, or buckwheat soba).
Basically, I'm confused. I know what works for dance, but I've never had to eat like a runner before. I know that the 50% recommendation is probably for people who are serious runners, so it's likely high for my purposes; and I also know what constitutes a "good" carb (e.g. whole grains, low sugar/GI, etc.). The question is, should I be adding more carbs to support the running? If so, I'll need to make some adjustments.
Gosh, this was long. Did I even say anything?

Your help is most welcome.