I suffer in the heat, mainly because I weigh about 225 pounds.
I run with ice on my head.
Ice on bare skin is too cold to tolerate, so I put the ice cubes in a cut down cotton sock and wear a hat to hold it in place. Cool water dripping down your face and neck does wonders. You don't want super cold ice that slowly produces water, you want ice at about 20 degrees that will provide cool water right away.
I also run with an iced water bottle in my hand. It is so cold that I can only tolerate it for a couple of minutes before I have to switch hands. I use it to drink from and splash cold water on my chest and back, and the cold hands also helps shed heat.
You can put ice cubes in the bottle, or fill the bottle 1/4 with water and put it in your freezer at a slant to get the ice. I often go through several such bottles. Quart gatorade bottles work, but I prefer the 20oz bottles because they are lighter and handier.