To sign up for the full or not? That is the question

So...our running team mates are looking at the Kasumigaura Marathon in Japan on April 19, 2015. I have been down with a bad cold the past entire week and a super hectic work/ministry schedule. The 10k run yesterday was the longest run in 10 days and it truly felt like a whole marathon. Had to rest the entire day afterwards! Could I still multiply it four-fold at a decent time?

I want to be strong but not work for it.
I want to be fast but not have to do speedwork.
I want to be slim but not have to control my eating habits.
I want to PR but not have age work against me.

I cannot have all my wants without putting in the work...and praying like anything. There are days where I absolutely dread the thought of taking the first step to start running. But I know it's because I'm not in top shape.

Here's to hoping I know for sure what to do when registration starts on December 3.

https://www.kasumigaura-marathon.jp/english/index.html

Update;
I joined Kasumigaura last April 19 and finished 4:46. Not my best not my worst. Best part of all:  I managed to recover most of my speed back for the training runs with my half marathons at 2:12. Haven't seen this for a couple of years!