Growing up I played (American) football in the south and during camp we would be up at 430 to do county fairs (a type of brutal workout). It always ended right as the sun was coming up at 6. The feeling knowing that most hellish part of the day was over and watching that sunrise covered in mud and probably still out of breath during the coolest part of the day on the way to breakfast was something almost heavenly. I'll still do metcon type workouts in the morning just to get that feeling.