Undergraduate / "MUN Club Leader at school" - activities, Common App Short answer [2]

Promt
Please briefly elaborate on one of your extracurricular activities or work experiences in the space below (150 words or fewer, 1000 character maximum).

Response
Model UN is one of the most significant elements through my high school life. At first, I was just a member of school MUN Club. From there, I learned about MUN for the first time and attended several club meetings. Later I participated in some large-scaled conferences and started to be familiar and infatuated with Model UN. In Grade 11 I became the leader of school MUN Club. As a leader, I have to in charge of the whole club, including recruitment of new members; leading new members into the world of MUN; contacting conferences and for them. I had many "first times" from MUN. The first time to give a speech in front of a large amount of people; the first time to design a recruitment poster; the first time to do all the logistical works and took care of them while we went out taking conferences. I received unforgettable experiences from MUN.

154 words in total.

I think my answer is quite flat....
If there is any gramma mistakes, please also tell me~
Thank you