I've done 7 runs of 18 miles or more. 5 of those were 20 miles or more. I've averaged over 70 miles per week. I've topped 80 miles in a week 4 different times.
I didn't miss a single scheduled tempo run. I did every VO2 workout whether I wanted to or not. I've done back to back long and medium long runs. I've beat the pavement before 5:00 AM to get in 15 or more miles before work.
I've been very careful with my diet. So much so that I've lost 8 or 9 pounds since I started 18 weeks ago. I've passed on cheeseburgers, fries, and desserts (well, not always desserts, but I've missed a lot of desserts) because I was picturing some number less than 3:15:59 on the clock.
Now, all that's left is the simple task of racing for 26.2 miles.