Here are 14 motivational sentences for junior high school students:

1、Never give up! Perseverance is the key to success.

2、Dream big and work hard, because success is always achieved through hard work.

3、Success is not a destination, but a journey of continuous learning and growth.

4、Your potential is unlimited. Believe in yourself and never limit your dreams.

5、Failure is not the end, but a stepping stone to success.

6、Challenge yourself and grow out of your comfort zone.

7、Never be afraid to set big goals, for it's through setting big goals that we become more successful.

8、Stay positive and keep a growth mindset; learning never stops, and success is always within reach.

9、Success is achieved by taking small steps consistently in the right direction.

10、Your efforts will pay off in the end, so keep pushing forward with confidence.

11、Be brave and face challenges with courage, for it's in our struggles that we learn to grow stronger.

12、Work hard to create the future you want and have a vision of where you want to go.

13、Learn to accept mistakes as valuable experiences for learning and improvement.

14、Trust yourself and trust your dreams; there is no greater support system than inner confidence.

Hopefully, these encouraging short sentences can serve as motivation for you during your school days.