Something that often comes up for athletes is heat acclimatization and summer training. Summer can make even the fittest athletes crumble under the intense pressure of heat and humidity. But, there are tricks to get through the summer days and still have effective training sessions. You could start by freezing a bandana, visor, or a small towel so it can thaw out on you. Plan your run strategically to pass water stops. Mentally, come to grips with the fact that a stop for 30s in the shade to cool down does not mean your workout was bad or that you suddenly are out of shape. It's an opportunity for your body to catch up and begin sweating a little more to get you ready for the rest of your workout.
The folks at Precision Hydration have also put together a summer hydration plan and approach to manage the heat and the demands on your body. This is a two part read.
Part 2 - suggestions for training in the heat