A buddy of mine got "Deep Vein Thrombosis" on a flight to Australia, he is one of the healthiest guys i know, he works as a mechanic all day, and goes to the gym for 2 hours a day, all of a sudden on a flight to australia when he was about an hour away his leg started hurting real bad, and he ended up having to go to the hospital as soon as they touched down, he said he was lucky they did, cause the clot apparently can kill you instantly, its scary stuff for people like me who sit on their ass all day for a living, i try to be active by playing various sports and hitting the gym but it doesnt change the fact i spend 6-10 hours a day on my ass, and another 6-10 hours a day sleeping.