One possible version：
High school is regarded as the best time in a person’life. As a senior 3 student, it won’t take long before I graduate. Now, I have much to share with my fellow students.
Firstly, I would like to show my appreciation to those standing by me all the way, teachers, parents and friends included. Without their help and advice, my life would be different.
Secondly, I’ve made up my mind to make every effort to study at college,for I believe hard work is the key to success. Meanwhile,physical exercise and recreational activities are also dispensable. Life without sunshine and laughter is bound to be a failure.
Finally I hope that all the younger fellows always keep your dream in mind, by which you will be highly motivated all the time, without doubt or hesitation. Even if sometimes you slack off, tell yourself that tomorrow holds the miracle. Just one more day may be all it will take to realize your dream.