Four weeks. Four weeks from today I'll be in Philly, getting ready for the culmination of more than six months of work.

Now it gets serious.

Not that it hasn't up until this point. But now it becomes more than just this vague, months-away event. This is exhilarating and terrifying at the same time.

Friday's 20-miler is key. It made me feel good about my prospects again. It's easy to fall into doubt and worry. After all, until Friday, I'd never actually run 20 miles at one time before. Yes, I have completed two marathons before, but I never, ever, say I ran them. If I do, it's a slip. I have completed them, but running stopped well before mile marker 20 came along.

This gives me hope for what's to come. I've done my long runs and emerged on the other side. There's still more work to be done, but it's about to go by quickly.

Because the Philadelphia Marathon is four weeks away. It's horrifying. It's nerve-wracking. But more than anything else, it's exciting. And that's a good feeling to have.