In hot weather (when I do most of my long rides) my stomach usually cannot handle real food. I bring one packet of gu per 10 miles, then throw in 1 or 2 extra packets since you never know when you'll wind up spending a chunk of time on the side of the road dealing with a mechanical problem. (It rarely happens, but I like to be prepared.)

I also start the ride with 2 bottles of gatorade. After finishing the first one I refill it with water at a reststop and drink water for a while, saving the second gatorade bottle for later in the ride. Even though they usually have gatorade at the reststops, I figure they might have a flavor I don't like, so I bring my own.

At each reststop I'll have one or two gu packets and some water. If it's really hot, I might have almost a whole bottle of water at the reststop and then refill it before hitting the road again. I try to drink at least one bottle per hour depending on the weather.

I'm not very good at opening gu packets while I'm in motion, so if I decide I'm hungry while I'm riding and the next reststop is still a ways away, I'll pull over for a minute and have a quick snack.

By the way, make sure you have a drink with every gu packet. The recommended amount should be on the packet.

I do most of my riding by myself. This summer part of my prep for the Livestrong Challenge was to play a cd with a some good uptempo songs in my car stereo over and over during the days leading up to the ride, so I would have the songs stuck in my head while I was riding. That helped alot. I also realized that one of my college's fight songs has the perfect tempo for riding, so I was humming that to myself for a while and it got me up some pretty tough hills.