1600s let down

Planned:
5 x 1600 Starting at 6:00 and dropping 4 seconds per interval.  3 min rests.

Actual:
83F, HUMID, slight drizzle for the start of the workout, puddles on track.
1 mile w/u
4 x 1600 - 6:00, 5:56, 5:52, 5:52
800 - 2:44
.5 mile barefoot c/d


Sort of broke on this workout - finally had a track workout push my limits...  I really need to start bringing water and ice to these afternoon workouts because the heat and humidity killed me on this one.  Between each interval I jogged over to the water fountain to splash cold water on my face and neck, but I was quickly overheating during the intervals.

The goal of the workout was to really focus on split times.  I've been pretty bad about judging pace lately, so I needed to focus on hitting good, even splits instead of just making up time to hit the overall split.  Also, by getting progressively faster I would work on the negative split side of my racing.  The intervals would start at my Cruise Interval pace for my half mile time and work towards my paces from my 5k time since I've been finding that the half marathon pace workouts seem too easy.  Last time I did a 1600 workout I managed to run 4 at 5:53 or faster, so I figured this workout would be no problem.  Different day, different temperatures, whatever it was, this workout got the best of me - I just hope it's not a sign of possible over training already...

First 3 intervals went alright.  1st interval the splits were dead on, 2nd interval the splits were off and I made up 6 seconds in the final lap, 3rd interval the splits were dead on again.  For the 4th interval the first 800 was on, but the second 800 was slow.  I was hurting as I started the last interval, but went through the first lap right on pace despite feeling slow and decided I would keep going as long as I was hitting the splits.  I went through the 800 mark 2 seconds slow, thought I would keep going but 4 strides later decided I was done.

The mental indecision / weakness has me more worried than anything else in the workout.  It's easy to sit here and say it was stupid and I should have kept pushing, but in the moment I just let it go.  This is a problem with running alone, and something I'll really have to deal with before Marathon time, knowing that pushing through the wall will be the biggest challenge I face in Chicago.