Your friend wants to start a new hobby but can’t spend any money. What would you recommend and why?

Reading- in library, or near by book store- frugal
For example: only one class I used to go to near by bookstore and read books. that had improved by vocabulary, sense of tackling problems
Another : exercise
Running. For example: One of my friends runs everyday 5 miles. He worte a blog on journey towars his fitess. it was absolutely smart way to stay healthy and active