I've just completed what is likely the most ambitious 20 days of training in my life. Since the beginning of the year I've run 292 miles; XC skied 95 miles; biked 93 miles; and spent over 5.5 hours weight training. Total is over 66 hours of training so far in '08.
Best thing about it is that my body has handled it all with no problems to speak of. Despite feeling great though I'm going to take a mellow week this week and then try to put in 7 days straight of at least 20 miles of running next week. The idea here will be to simulate my race pattern of putting in long steady day after long steady day. There's obviously a big difference between putting in ~20 a day and 50-60 miles a day as I'll hope to do during the race, but at some point one must draw the line at how much volume of training is actually helpful. I think my body will comfortably handle 140-150 in one week of training (I've already had a few 7 day periods this month in which I've done over 120 miles with some other forms of training mixed in), but if I were to try much more than 150 I think my body might suffer negative effects from it. I've got to save those negative effects for February 24th.
It's a good feeling to be in such strong physical condition. Runs that would have taken a large amount of energy out of me just 6 or 8 weeks ago feel like recovery days right now. An example that comes to mind is the 20 mile run I did on Saturday dragging my sled full of gear. Total weight was 36 pounds and it didn't seem to slow me down at all. I was a bit tired out after the run but within an hour of stopping I felt completely recovered and my heart rate was back to it's normal resting rate of 40-43. At any other point in my life a 20 mile run would be my long day of the week and now I've worked so gradual up to this point that a 20 miler is more of an active recovery day.
I've still got a lot of work to do to be ready to take that first step on the 24th of February, but I sure feel a lot closer to being ready to handle this race (both physically and mentally) then I ever imagined I would be.