When it comes to sports there are three kinds of people. Firstly, the couch potato, scorning those who exert themselves enough to break a sweat; secondly, the average enthusiast, who enjoys working out now and then; and, finally, the hard-core fanatics. This last category includes not only professional athletes, but lovers of extreme sports – those seemingly addicted to danger. If you are an adrenaline junky looking for your next fix, look no further: here are a roundup of five of the most exciting (and risky) sports to try. 1. Big-wave surfing Anyone who has watched clips of the world’s…