Learning a language
The importance of a large vocabulary in your target language can't be overstated. Some are convinced we can converse quite comfortably with just a few hundred words. There are lots of articles on the topic. I don't agree.
Learning my grandmother's life stories helped me to reconnect with my own Indian-American and Indian-Canadian identity in a way that Bollywood movies never could. If you're the first-generation child of immigrant parents, you owe it to yourself to learn the language of your grandparents. Spend some time with them and ask them about their life. Go deeper than the mere sequence of events you might've never ventured beneath because of language barriers. It could just be the key to unlocking dimensions of who you are. And if history is cyclical, perhaps who you might become.
For travel, for work or just for fun!