[GianFabien]

I guess there are lots of different interpretations of what it takes to be "smarter".

Personally I've learnt several foreign languages to the point where I can read classic novels in one of them. Different cultures and idioms help me see things in a different light.

I have also dabbled with woodworking, gardening / hydroponics, electronics / embedded systems. Read more widely in the fields of chemistry, biology and linguistics. Also read biographies of notable people.

Do I feel smarter? Not really. The more I learn and discover the more I realize all the things that I know nothing about.

[tayo42]

Language learning is mostly hard work and perseverance and time? Which I'm pretty sure is what "smart" usually is.