Let's look at the facts: there are 40 days to go to the race. Wisdom, and Hal Higdon, tell us that if you can do 20 miles, you can do 26. So with a 2 week taper, you have roughly 4 weeks to get to a 20 miler. Did I get your earlier message right (or perhaps it was your email)? Have you managed a 17 miler so far? If so, it's only a small hop to 20.
The big unknown is your asthma: how bad it is, and what the weather will be like for the next few weeks. Echoing Sweder, here in Berkshire, spring is definitely on the way. The last few days have been sunny and actually warmish (though cold at night). You might hit lucky, or you might not.
As it's an unknown, let's ignore it for a moment, and concentrate on the things you
can control. You can aim to maximise (within reason) your cardiovascular fitness, and this is where the gym can be really useful. Don't think that the treadmill is your only option. I know you're not a big elliptical fan, but what about the bike and rowing machine? You can get a great workout on the latter, even if it's not something you'd want to do for longer than 20 mins or so (IMO). Cycling is really good cross-training for runners, and can certainly get the heart-rate up. If you can talk yourself into a spinning class, you may never reappear -- they are highly addictive. But spinning is also a brilliant fat-burner/fitness builder.
Instead of contemplating 12 miles on the treadmill (and I wouldn't do that either), think in terms of time. You need a 2 hour workout. Why not put all those activities together to come up with a 2 hour+ session? For a long session, I used to do 10 mins on the rower as a warm-up, then a routine of 20 minutes on the elliptical, 20 on the treadmill and 20 on the bike, and repeat if I had to. A long session is much more manageable if you can break it down into chunks, just liek you do for the race itself.
The asthma is a curse, and we know you've had all sorts of other ailments and accidents. The fact that you've got to where you are is pretty astonishing, so feel proud of that. But it seems to me that your biggest battle at the moment is with that old enemy - self-belief. All I can offer here is my own experience, which is that if you can feel good about yourself, you can easily swat away the doubts. And spending some time in the gym doing a
variety of these things can do you the world of good. It may not be quite as good as getting back home after a 15 miler or so, but a good couple of hours in the gym isn't that far behind. If the weather improves and your asthma recedes, allowing you to get out for a few miles here and there, so much the better. You can very quickly feel much. much better about the race, and your chances.
Marathon sages will talk about getting the miles in your legs, and stacking up those long runs, and if you can, great. But I really do think that if you have to scale back on the miles, the gym and other CV activities like road-cycling and long strenuous walks, can really help. By far the worst thing to do is to get fed up and to really scale back on doing anything. As an expert in this 3rd option, take my word for it. People have said kind things about me in this thread that I really don't deserve. If I'd been aiming for a UK marathon, I don't know if my resolve would have been so strong, but with an airline ticket and hotel room paid for, it was different. I wasn't going to chuck away £1500 so easily! That was a big part of the motivation, and you need to find some motivation from somewhere too. Once you have that on board, the trips to the gym and/or the two or three long runs you have left will become non-negotiable.
The other thing to think about is managing your own expectations of the race itself. How bad is it to run-walk a marathon? Not bad at all. Hal likes to relate the fact that his son ran a 2:28 marathon by run-walking! Suzie of this parish is a great believer in run-walk and turns in perfectly creditable times. I read something recently... an actor I think, said, when asked how he coped with stage nerves, said "I just turn the 'What if?' into a 'So what?'" It's sometimes worth taking a step back and asking why we get so worked up about these things. Supposing you chug along at the back, enjoying the event, having a natter, and walking for a minute or two each mile? So what? It's not illegal.
Equally, it's not a crime to decide not to do the race. I didn't do the Wokingham Half a couple of weeks ago because of injury. No one minded, or if they did?
I may well not do Reading in a couple of weeks. It doesn't matter, apart from the fact that I like their medals. When all's said and done, if you think you're just not able to do the race, no one will mind -- apart from you. You could decide to do it next year instead, when perhaps a few of us might be there too.
Personally, right now, I would try to think positively, and aim to give it a real good do. It's amazing how fortunes and self-confidence can change in just a few days. But if your asthma or your other issues become too much of an obstacle, just give it a miss. It's not from a lack of effort or determination, that's for sure. One of the good things about any running community is that we all know what it's about. Everyone here will understand totally.
