I really don't get this. Are you sure there wasn't a big dog hunting you or so?I've never been so scared and it takes a lot!! It was the fact my head was saying slow down as I was going down hill and my legs were saying I'm trying to lol
Because, if there is any big benefit of fixed gear, it's that it HELPS you to slow down. ON TOP of using the brakes, you can resist the pedals, slowing down even faster.
Just stand up, and everytime a crank comes up behind the bottom bracket, resist using that leg, using as back the other leg and arms on the handlebars. It's easier (but somewhat less effective) to concentrate on / use a same leg to resist. I bring a song in my mind when doing it (Links zu links zu links 2 3 4 links - rammstein).