Training for a marathon is a huge time commitment. But the actual training miles themselves are mainly relaxing. You don't do many runs (other than the 14 mile run from hell) that hurt for the whole run. Almost everything is at a very manageable pace, after all, you have to maintain it for 26 miles.
Contrast that with the training I'm doing for my next half. Monday, I did 4X1600 intervals while panting and grunting and pushing myself to the extreme for each one, and, mind you, noting that my fastest mile of 7:22 is still off more than a minute from last year's fastest speed training. Yesterday, thankfully, was 3 easy miles to recover. But, today, I was back in the masochist zone for a 55-minute tempo run. Again, I pushed myself to the limit of my physical stamina, and, I couldn't help but note that I'm slower than the last time I did this type of training.
Basically, one thing that sucks about shorter distances is that it's reasonable to train for speed. Which is fun, after you've received the benefits. But while you are doing it, especially when you are doing it for medium-length distances, boy does it hurt.
Here's to hoping I can retain some of my former fitness in time for the race. Beforehand would be nice too. I'd really like to enjoy some of my speed training instead of having it all hurt...