The computer helps me push myself. I usually have the speed and miles displayed but I do check my average speed during the ride and tend to want it at a certain point and will push myself if I start to fall off. I do also switch over to time every once in a while to check my cadence but I am to the point that I generally know where I am spinning...usually around 70-80 and I can tell when I am slipping and consciously adjust.
I also have a tendency to not be comfortable unless I am really pushing myself. I will start out thinking I will take it easy and the next thing I know I am pushing hard and actually having more fun. I am not a good leisurely rider. One other thing is that whenever I am being passed, passing someone or coming at another biker, I tend to start peddling faster and harder. I think it is a competition thing. lol