Once you have a positive attitude about college, you must then exert great deal of effort to achieve your objective. Remember, nothing in life worth having comes easy. The amount of work you put into preparation will determine your success. Maximum effort in school and in your personal life will give you an opportunity to be successful. Your effort will, in the end, be what makes the difference.
Great effort equals great success.
If you aren't successful in high school, colleges will not accept you. They are reluctant to accept students with poor GPAs because they believe this indicates that a student cannot do college level work. Colleges also believe a low GPA means a student hasn't put forth maximum effort in the classroom. If you have a weakness in a specific subject, ask for help. If getting that help requires you to stay after school, then that is what you must do.