I just bought a Trek 7.2 FX WSD about a month and a half ago, so I am pretty new to cycling. I have been working gradually on increasing distance and it has been going well. Now that the hot summer weather has started, I have been having some trouble with over-heating. I have been a competitive horseback rider and have always struggled with some sensitivity to the heat (I feel I'm more prone to overheating). I try to wait for the cooler time of the day, I drink water, and take some breaks. Any other ideas more specific to cycling would be greatly appreciated! I have surprised myself by becoming really into the cycling and would hate for this to detract from my progress and enthusiasm for my new sport/hobby.

Take it easy while riding. Make sure you're in a good gear (not spinning around too quickly in a low gear, or having to really mash the pedals because you're in a high gear) and comfortable while riding. I assume you already have a water bottle cage--maybe put on a second if you can for extra hydration. Be sure to be hydrated already before you ride. Wear some comfortable clothes--you can find shirts that breathe, and have panels for air flow.

Invest in some good lights and ride in the wee hours of the morning.