Your chair is too high. It is cutting off the circulation to your legs which can result in varicose veins which is far worse. Try to get a lower chair, or a small stool to elevate you feet. This will reduce pressure on lower back as well, and help increase circulation to your legs. They actually carry them in office supply stores, for this reason. If you are sitting on something and your feet aren't touching the ground and even if they are, the pressure behing your thighs will cause poor circulation. Try to resolve this before you start having varicose veins, and also, avoid crossing your legs at all cost as this too is an obstruction of the circulatory system
