One more thing, be sure and eat a GOOD breakfast before going on a group ride (or really any ride). I find that what I eat makes a huge difference on my performance.

I was in "Loose Weight" mode for so long that I found it hard to stop watching the calories after I reached my target weight. Now on days I know I'm going to ride after work I'll eat a bigger lunch that I normally would to be sure and have the calories to do well on my ride. I can feel the difference during my ride if I don't eat well.