Don't say that if you don't study today, there will be tomorrow, and if you don't study this year, there will be next year. There is no light in the sun and the moon, and there is no delay in one year.
Teenagers are easy to get old, and an inch of time is not light. They can't feel the dream of spring grass in the pond, and the leaves in front of the steps are autumn.
It is never too old to learn.
If you don't make up your mind, you will end up useless.