Should I run 15 miles?

I haven't been talking about running, have I? Oh, don't go crazy—I am definitely still running. Three times a week, two short weekday runs and a longer weekend run. But I'm totally in this funk with it. I am loving the freedom of running as I see fit. I'm constrained by this need to train, I'm just running for the love of it and because it feels good. I am feeling strong, despite not really doing anything special to improve.

I ran a 5K here in my hometown earlier this month and it went fantastically.

I was the 4th female to cross the finish line, and the 3rd female in my age group to finish. Yes, the top four female finishers were all in the same age group. My age group. We basically kicked ass.

I even clocked a new PR:

Again, totally not training. But I've clocked a few runs with one of my trainers, who happens to be a high school track and cross country coach. I think he's pushing me to be faster, and it's obviously working. With his help, I've even clocked a 6:55 mile. That's way fast for me.

But, here I am.

One thing I've been thinking about is the Fifth Third Riverbank Run in Grand Rapids. It's a 15-miler, which would be the longest distance I have ever trained for. Not gonna lie—I sort of want that medal just to show myself that I can do it. But I'm also not gonna lie about the fact that the idea of training for it makes me want to crawl into a hole.

According to the training plan I downloaded from the website, I need to start building distance this weekend. So, instead of my usual 6-miler, I'd need to log a 7-miler. And I just don't know.

I spoke with my running buddy about my lack of motivation and he thinks I should focus on shorter distances this year. I usually focus on a handful of half marathons every year. Focusing on 5K and 10K races wouldn't really impact my existing fitness schedule like training for a half marathon could.

Translation: My running and fitness is as such that I don't really need to train for three or six miles. I'm basically already doing that via the three runs I'm currently completing each week. Minus the pressure, which is great. Here's what my weekly schedule looks like:

Monday: Barre Fit
Tuesday: 3-Mile Run
Wednesday: HIIT
Thursday: 3-Mile Run or Spinning
Friday: PiYo Live
Saturday: 6-Mile Run
Sunday: Rest

So, I've got the rest of this week to decide what a girl should do.
Also, I need new shoes. So the search begins for those, too.

Question: What do YOU think I should do?