To get to the most out of language learning, your learning must serve a purpose. By identifying your purpose in language learning, the drive to learn will only be strengthened, and this therefore is a key tool. A sense of purpose is a highly important key tool, no less. It's worth sitting down and looking at why you may want to learn a language, so we'll go through a few reasons here to help define your purpose for learning.
The most obvious purpose for learning a foreign language is for a holiday. Many holiday destinations around the world can be enhanced by learning a bit of the local language, to improve relations with locals, build friendships, and learn more than you otherwise learn about the place which is not ordinarily accessible to those holidaymakers speaking only English. I always try to learn a bit of the local language, even if just a few words, as a courtesy.
You may find that, with the world getting smaller, there are members of your family or circle of friends who don't have English as their first language. To facilitate inter-cultural understanding, learning their language can help, You may also wish to bring up your child to be bilingual. I am proud to count many people amongst my friends and family locally and globally whose first language is not English and who are bilingual or multilingual.
One of the first arguments against learning another language is that everyone apparently speaks English, but having travelled widely to countries on three continents, I can easily confirm that's not true. Even in countries which are popular tourist destinations for English-speaking people, once you take even just a few steps into a side street away from the beaten track, you soon encounter a wonderful world where English may not be spoken. By struggling with a few phrases of faltering French in a restaurant in a back street in the Montmartre quarter in Paris, we got better service than the British couple on the next table who insisted on doing everything through the medium of English in the middle of the Francophone capital. My wife and I have been able to get a far warmer welcome through usage of foreign languages. We have even gotten a better deal in some shops in some countries because we were able to negotiate prices at a basic level in the local tongue. We are usually able to learn more than we would otherwise have learned if we had only been bound by the limits of the English language and locals' capability to speak English.
One key purpose for learning a language is moving to another country. You may be moving to a country for a period of study, because the culture may interest you, your employer is sending you there to work, or you might be teaching English as a foreign language. Either way, you'll need to have some way to work out what the menu says when it's time to eat, or what the electric bill says when it falls through your door. I lived in China for six months during a gap year, and found myself having to pick up the Mandarin Chinese language very quickly!
You may wish to explore your heritage and identity through language. In Wales, Cornwall, the Isle of Man, Ireland, Brittany and Scotland, people are learning the ancient Celtic tongues (or reviving them, in the case of Cornish and Manx) to preserve and promote their unique culture and heritage. Similarly, with genealogy, if your family comes from central Europe for example and you are researching your family tree, it may be necessary to learn the old family tongue from several generations back.
There may also be some information in a language which you may need for study which is not so readily available in English. A bit of language learning can open up new avenues to you for research that were previously closed due to the language barrier. I spent a week in the Sorbian region of Germany in the summer 2007 in various museums, bookshops and libraries for a research project I was working on. Apart from a paragraph on the English language Wikipedia website, there were no materials available in English on my chosen field of research, so using German (and a tiny bit of Sorbian that I picked up in the week I was there) was essential.
Even if you don't go abroad, language skills are highly marketable and attractive to an employer, particularly if an employer does business abroad or is considering expanding into Europe or further afield. When I worked with the insurance field in vehicle accident management, I often was appointed by colleagues to examine foreign language insurance documents and driving licences and calling abroad to get vital information, cases which normally would not have been resolved so easily without my language skills. Languages can also open up business opportunities in parts of the world your company may not have previously considered.
The best part, though, about learning other languages is that that my efforts to speak another language have always been appreciated, and with a few words, bridges have been built. Nelson Mandela, the late President of the rainbow nation of South Africa said: “If you talk to a man in a language he understands, that goes to his head. If you talk to him in his language, that goes to his heart.”