

Practice juggling. Buy 3 juggling balls (you know those bean bag types that don’t roll away), and keep them with you. Don’t use tennis balls, because they have a tendency to bounce and roll. When you have some downtime, start practicing. Watch a few video tutorials to get the hang of it.
If you can have a backpack with you, consider bringing a tablet with you. If you have one with a pen, you can draw. Watch a few more tutorials, and learn to draw something you like. Landscapes, portraits, fantasy dragons, pokemons whatever.
Tablets are also fine for reading ebooks. Check what your local library has to offer. Maybe you can borrow library books and read them on your tablet.
Intelligence is such an elusive concept, but here goes anyway…
Knowing stuff makes you knowledgeable. You’re either born intelligent, stupid or somewhere in between. No amount of studying will ever change that, unless studying also involves copious amounts of alcohol. In that case, you’ll only get dumber.
Anyway, studying gives you information and tools, and what you’re talking about is a bit of both. If you go through a training system like that, you’ll be equipped to process and evaluate information, but none of that changes how intelligent you are. Sure, you can sound really smart to other people by using fancy terms and explaining complicated things. Those words alone don’t make you intelligent. Having the innate ability to understand that level of information does.
I’m sure there are really smart people living in rural parts of India where they don’t learn to read or even count very far, but they can do really clever stuff when hunting birds or weaving baskets. Even though they didn’t receive much education beyond what they learned from the local villagers they can still be intelligent. If they were born in a wealthy family in UK, these people would probably go to Oxford and graduate with a PhD in no time.