actually, there is no such criteria and it is impossible to give you a definitive answer of what you should do in your spare time-because, after all, it is your free time, so you should be the one deciding what you want to do with it.
However, in response to the information you have given
-Watching anime a lot-actually it doesn't really matter if it allows you to effectively relax and go back to study-ever heard the phrase 'study hard, work hard', as long as you watch it after you finish doing your allocated work for the day and use it if possible, as a condition or reward upon condition of a certain amount of study-there is no problem(just make sure you are finishing your homework and assessments and assignments on time as well)
-I'm not the sporty type-ok, you don't need to run a marathon-but you should do some sort of regular walking if you don't walk to and from school-sometimes a stroll is all that is needed, or there are some X box type games that promotes physical exercise but within the comforts of your living room-so you can try it with a friend-so you feel more motivated, just a fact, exercise can stimulate your mind and improve concentration span-and a healthy body will always be better to cope with situations of extreme stress than a less active one
-Any ideas to pass the time?
Below are my top suggestions, but you are free to reject them all and do something you like
1)Watch/listen/read related material related to your subjects-so i.e. if you do legal studies, you might watch the news to understand the effectiveness of laws-increase your understanding, if you do science subjects-you might watch lectures/short videos on related, but not identical topics to what you are studying-basically do something that increases your interest/passion in the subjects you are studying
2)Spent some time with your family-communicating with them, spend some time with your siblings, establishing strong familial connections will provide a supportive, understanding familial environment which will improve your studying efficiency since your family will gain a greater understanding of your feelings and needs during the HSC and can undertake measures to support you-both short term and long term
3)Do some volunteering-if you have enough time, go out with your friends-i.e. on Friday night for a movie for example, and perhaps help out other people in your cohort struggling with the materials taught in any subject or ask your teacher any questions you don't understand or do extra practice for your subjects
4)pack up your room, make sure you have a welcoming/neat study environment, organise your study files and notes-both in physical folders and on your laptop, make short term and long term goals-evaluate them, make study schedules and to-do lists.
Hope this helps-do what you like, make sure you have enough time for studying, rest and having fun-when you are able to maintain a balance, it really doesn't matter what you do in your free time-as long as you are using it productively and you feel happy doing the things you enjoy
