Believe it or not, exercising a lot does not give you a free pass to sit around for hours on end. If you find that you are sitting for hour after hour, day after day, you might want to find an excuse to get up. Sitting a lot increases your chances of developing a blood clot. This is particularly true of overweight individuals, pregnant women, and anyone who has undergone a medical treatment such as surgery recently. Get up and move around at least for a few minutes every half hour to hour.