Marathon Training Begins

Monday officially marks the beginning of training for the Green Bay Marathon. 16 weeks of speedwork, long runs, and ice baths.
I'm really nervous about it this year. I'm still feeling very insecure about my running after taking a month off for my sinus surgery, and only running lightly for the month before that due to our move. I've had some good runs (last week's spiritual four miler and then the snowy seven miler with Jo) and some really hard runs (last night's tough 5 miler where I wanted to quit after 1.5 miles) but I'm still much slower than I was a few months ago. Last night I struggled through my five miles, taking three brief walk breaks and ending up with an average pace a full minute slower than I averaged three months ago. Meanwhile my running partner is getting faster and faster and has a much better mileage base to start training with. I've got some real catch up to do. And fast.
Our plan has us running four days a week with weekly long runs ranging from 10 to 20 miles plus one speed workout a week. We will run at least two 20 mile runs before the marathon. That's a long run, my friends. Ever run 20 miles? At one time? Trust me, it's a long way. And how about 26.2 miles? Just so you're clear, that's even further. And that's what I'll be doing again 16 short weeks from now.
God help me.