This hot weather makes exercising outdoors tough. I used to go for a run and then come back and drink water, but because I'm sweating so much, I need to rehydrate while I workout.
One of my new favorite finds is this water waistpack known as Strider made by Ultimate Direction.
It is a waistpack so obviously you wear it around your waist, and the straps are adjustable so you can get it to fit as snug as you like it. The water bottle fits right into the curve of your lower back and the little zippered pouch rests on your left hip. The small amount of weight from the water bottle pressing on my lower back feels really comfortable.
It comes with a water bottle and the pack is so lightweight, I hardly feel it when I'm running or bike riding. The tiny pouch is 8 inches long, so it's big enough to fit some money, keys, cellphone, and a pack of tissues (or whatever other small items you like to have when exercising outside).
You can order it online from Rei.com for $30. It comes in black, as shown, or sage gray.