i too ride in Denver, and there is nothing here to stop me either at 43 and also over on the scale. I use a camel back clone and fill the bladder w/ ice at work before I leave. Even if I take the long way home (15 miles, some 15 minute hills on my hybrid) I still get home w/ ice in the bag. Another trick I learned from my son in the MArines is to wear Under Armor skin tight Tee's. Instant cooling as you sweat, you don't have to soak a shirt before it cools you....
And like everyone else said: "Take it easy"
Tom