I have that same problem. If I'm riding alone, I just push. :-/ I'm a speed freak. The only way I can go slow is to have someone to wait for. And even in that case I act like a hyperactive dog, zooming ahead, doing circles till they pass and zooming ahead again.
Though my ride to the train station is only 1.2 miles, I managed to average 20mph on my way there. :-) Yup, I can pour on the power for ALL of 200 seconds.