"our school government campaign" - common app short answer!

My experience in our school government campaign transformed me from a mumbling, hesitating coward into a passionate and persuasive speaker.

My first attempt at speaking in public--blushing and muttering feebly--was a nightmare I am embarrassed to recall today. But I wouldn't let such failure stop me from chasing my dream.

I compelled myself to enlist the council campaign after I entered high school; I revised my speech many times, worked on my posture and poise, and struggled to conquer my fears. Little by little a boundless passion grew in my heart, a passion that would help me break through my self-imposed limitations.

My final speech in that campaign set the audience on fire. I can still feel my body quivering when I finished. I knew from then on I would always speak powerfully, from my heart. I would never hesitate again.

I have a strong motivation in my heart, which pushed me to break barriers every time I want to quit. I am not a native English user, so I don't know if this essay I wrote properly transmit my meaning, being impressive enough. Thanks for all the suggestions.

Idea is good, essay and English is fine too, only thing perhaps you should talk about a bit more is how you suddenly changed from a bumbling mutterer to an eloquent speaker. Did someone motivate you, inspire you to change? Or perhaps you can start off with your passionate desire to be a speaker and why, which motivated you to work harder .

Actually it was a process but not a sudden change. Every time after I quit doing something, there will be a harsh debate in my heart, a debate between the desire to shine, to improve and my fear to be embarrassed, a debate I couldn't appease. And that's how I finally compelled myself in that campaign in High School. It was a complete victory, in which I won the second place out of 40 candidates by total votes, quite a dramatic contrast to the first time I tried in my middle school.

It's about a long story, but I only get 150 words.

How could I present that...

Your English is well written, but I agree with MoonShadow, paint more of a picture of how you brought yourself to where you are now. Give some imagery of your nervousness at the podium or how you felt before you got on stage, or even your joy when the crowd appreciated you. Otherwise, as it is, it sounds great, I just need a picture to go along with it. :]