You should try to develop your own hobbies, even if you have only one. Because good hobbies can cultivate your emotions, increase your knowledge and enjoyment, and make your life interesting. People who have no hobbies will be very boring, and it is also easier to lack of friends. So you should try to discover what you are interested in.
If you are a quiet person who doesn't like strenuous exercise, you can learn yoga, calligraphy and flower arrangement. If you are active you can learn to dance, go to the gym fitness. This not only can utilize up the free time, but also can improve their temperament and enrich their ability.
If you are really not interested in something, then it is committed to learning, boredom is not as good as to go to study, you have more free time than others, there are more dedicated mind, not only to pass the time, but also to grow their knowledge.
If you are bored and do not want to use your brain to study, you can go to part-time. First of all intuitively, you exchange time for money and can accumulate an allowance. Secondly, you experience different roles and gain different experiences while working part-time, which is helpful for your future career.