Battling the Heat - who is winning?

As most all of my friends and family know, I have been battling issues with my hip and glutes since April.  This week, I felt like I turned a corner and have had great turns.  I started wearing my power steps again which seemingly were making all the difference in the world.  That is why I didn't think an 8 mile run was out of reach.
Alas, I forgot about the heat and humidity.  Although I drank a ton of water and sports drink yesterday, it wasn't enough.  Silly summer.
Our run started at 7 am and the temperature reading from the car was 76 degrees.  There was fog and no sun.  Perfect.
Early into the run, I was out of breath and struggling a bit.  By 3.75, my hip was sore so we stopped so I could stretch.  Every run this week had been good so what was up this morning?  We stopped for water around 4 to 4.5 miles and went on.  By the 6th mile, I realized my problem.  I was super dehydrated.  My head hurt, I didn't have a lot of saliva (admittedly, I am a spitter when I run so no saliva is rare), and my hip was still sore.  We decided to make the run only 7 miles.
Whew.  7.1 miles officially on the books.  In late March, I was running 20 miles with no problems and having the best time ever.  Now, I am super pumped about my 7.1 miles.
Today's lesson?  No one is immune to the heat.  I make a conscience effort to stay well hydrated, eat right, avoid the heat and humidity, and all the things that go into having good runs.  But today I battled the heat and I think we tied.  I didn't go as far as I wanted but I probably should have set my route so that I could have stopped sooner if need be.  We'll see what happens tomorrow in this war with the heat.
Be careful out there.  No one is immune to the heat and humidity.  Listen to your body and slow the pace or shorten the workout.  I speak from experience about listening to my body and the consequences when you don't which is a whole other post for a later time...
See you on the roads.