The value of a special sitting position

Traditionally sitting meditation involved sitting on the ground with the legs positioned in a special way.  The lotus position, which involves overlapping the legs, was the standard position. However, this position and even its modifications (e.g., the half-lotus) are difficult for most people who are used to sitting in chairs for most of their lives.  Fortunately, there are alternatives that are every bit as effective.
But why meditate in a special position anyway?  Why not just get in a comfortable chair or even lie down?  If you are too comfortable sitting in your favorite easy chair or lying down in your bed, you are likely to fall asleep.  The traditional meditation postures are designed to allow you to be comfortable and yet alert for long periods of time without moving.  Those who sit in these positions generally report that they feel more balanced than they do sitting in a chair.  The very specialness of the posture is itself a benefit.  If you meditate in your favorite chair or in bed, all the habits that go with that position can end up affecting your meditation.  When you sit in a special position, on the other hand, you are likely to associate it with meditation and find that it is conducive to getting more readily into a relaxed and focused state.
Even though it may appear that assuming a special position for sitting meditation is awkward and a lot of extra work, try it (unless, of course, you have physical limitations).  You will probably find that it is a lot easier and more satisfying to meditate in the special position.