You Must Be Trippin' - Avoid Deep-Vein Thrombosis: "Avoid sitting still for too long without stretching or standing. This is particularly an issue for frequent fliers, who can get confined in an airplane seat for many hours at a time. Even if you must inconvenience your seatmates by standing, make an effort to get up and move around every hour or two. The same advice applies to desk jockeys -- don't sit in that office chair all day without a break. You're asking for trouble."