What a question! It may seem difficult to answer it but the answer is pretty categorical: Yes. Anyone willing to learn a foreign language is capable of it.
There is another related question: is it easy? Now the answer is No. Everyone can learn a language although it requires time, an effort and the patience of a saint. Some people learn faster than others. And some have more spare time to study. However, in the end, you will speak a foreign language if you really want.
In addition, you need to find a motivation. Some people learn languages for professional purposes. Also, there are people who like to travel and need languages. Having a fiance is another good reason. In fact, learning languages can be just a hobby. Simply find your goal.
You need to be a bit tenacious and to study or practice everyday a bit and never leave it. Everyday you can do different activities such as your homework (if you are studying in a language school). You can also read articles or special books for students of languages. You can often listen to your target language (thanks to internet you'll be able to watch videos, television programmes or to listen to radio stiations). Search web sites to learn your target language (there are dozens of them) or to practice with native speakers (e.g. here).
Finally, never forget that if you work everyday, soon you'll notice your improvement.
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If you want to meet people and practice languages with native spakers visit Babelan.