Read more books. Honestly, I feel my IQ rise when I'm traveling for one main reason: Without TV I'm forced to read. Traveling inspired my interest in politics. It motivated me to become an animal activist. It made the simple act of stumbling upon an English-language bookstore or library a euphoric experience. When I read, I care about my world. When I watch TV, I don't.
Learn a foreign language. The strongest envy I feel is when I'm listening to my travel friends converse easily in two or three, even four, languages. Multi-lingual people are more intelligent, more interesting and more useful.
Take classes. Writers workshops, yoga, ski lessons all create fantastic environments for meeting likeminded people. Staying home with JuJu, my Tibetan Terrier/Poodle mix (aka "Toodle") puppy, does not.
Earn my living as a freelance writer. It's hard to travel when I'm working 9 to 5. I didn't appreciate what I had until I didn't have it anymore. Note to all my former and present editorial clients: Thank You. Working for you afforded me freedom, and freedom is truly priceless. P.S.: I'm still available for hire.