Maybe, learn something useful and interesting like programming if you know it already then you don't! read things about design patterns, garbage collection, or anything seems interesting maybe web development (what I'm doing now).
Or start a project think in any project even ones that are already made.
This is just 3-4 hours a day, go outside, run or walk daily, volunteer in charity, or even get a job, practise a new hobby, like horse riding, tennis, or something you always wanted to try, maybe cooking!
Read books, novels, go to the library and start reading, or start writing your own blog, or book.
That's what I would do if I had