In running

Why do I bet in running?????? as soon as I lay the horse, it seems to get an outboard motor from somewhere and zooms up to win. This has happened twice now at wolv and I need to learn the lesson!!!
When I trade I find that it works, yes it seems little return each time but I find that I am now doing 3 to 4 trades per race and able to look at the market and can get in out at the correct times, I just need to be more confident and do this rather than GAMBLE for larger returns. IDIOT!!!!!