Late run and thinking

I got a late run in last night (4miles) and had some time to think. I think overheating and dehydration are the cause of my problems on Sunday. My body is doing some strange things with temperature regulation. I have been cold for the last two months. So, I responded by overdressing on Sunday and my heart rate was way too high for most of the run and I was miserable. Last night I was cold for most of the run and my heartrate was fine and the run felt great. I am as surprised as anyone, but I can now crank out a four mile run and not feel anything wrong in my legs the next morning. No stiffness, no soreness, no discomfort during night. It is amazing. I wonder how it will feel when I hit my weight goal???