Get some fresh air!
We know what it is to be an Erasmus student: parties, bars, nightclubs, dinners, beer, tapas... Maybe it's time to do some sport. If you feel for a run, let me tell you the place I like the most. Carretera de les Aigües. Take a walk, run, meet with some friends, sit down and read a book... If you are looking for a place to enjoy nature while having one of the best views of the city, go there. You won't regret it.
How to arrive: You can get there by Ferrocarrils de la Generalitat (s1 or s2) and stop at Peu del Funicular. Then, take the Funicular (it's a cool experience as well), and stop at Carretera de les Aigües. If you are really brave, you can also go walking from your place. It's a great plan to get rid of a hangover!
For more information: http://maps.google.es/maps?q=carretera+de+les+aigues&ie=UTF-8&ei=x_9wUt-ZM9SR7Aao7oHABw&ved=0CAoQ_AUoAg