You should say:
When it happened
Who helped you to make the decision
And how you felt about it
OK, I would like to share with you the time when i made the decision to choose my major.
As you know, Due to the implementation of compulsory education, students all study the same courses in their high school, such as math english physics.
After taking the university entrance exam, i was puzzled about what i am supposed to major in.
So i ask my brother for his guidance.
My brother is a intelligent programmer, he take the position in Baidu as a algorithm engineer. And he gave me his advice with great enthusiasm. He strongly recommend that the computer science is well worth studying. Computer science is a domain that has a promoting prospect.
What's more ,as you know , we witness a rapid development in technology. Being equipped withsome knowledge related to computer science, we are able to keep pace with the times**
and acquiring the professional skill like programming, i will be more competitive while seeking the job.
And now i am a senior student ，I never regret this decision i made.
I am really grateful to my brother
implementation 政策的推行 /ɪmplɪmen'teɪʃ(ə)n/
puzzle /'pʌz(ə)l/ 困惑
domain filed 领域
diligence [ˈdɪlɪdʒəns] 勤勉，勤奋