On Sunday, I did my longest training run ever: 20 km (12.4mi). In preparation for my first half marathon, the longest I ever ran was 18 km. Now, I know very well that a couple kilometers on race day isn't necessarily that big a deal. If anything, your total training volume is far more important then just the weekly long run. If I'm running once a week and doing 20, I'm in far worse shape then if I'm running a total of 45 km, but my longest is only 16.
Having said that, there is a certain mental edge you get from running as much as, or even over, the race distance. It's an advantage you can get when you are running the shorter distances. Once I start doing marathons, it's no longer an option to overrun the distance in training.
On Sunday, I felt strong and capable. It worked me, but didn't push me to my limit. I will have 4 more runs prior to my half mary of distances over 20 km (as much as 24). Four more chances to get that feeling of going the race distance (or further) prior to my race.
Last time, I went into the half marathon believing (hoping?) that I could finish the distance. This time, I'll go in without any doubt. This time, I won't crash and burn. I'll just burn up the pavement. (okay, probably not actually fast enough for that.)
Am I crazy for doing these distances?