Health benefits of meditation
Meditation is a very powerful way of controlling physiological processes in our body. One of the most profound change that happens is the slowing down of the metabolism. A noticeable influence of blood pressure, which drops much lower than normal. The heart rate also slows down. The blood flow however increases. This is due to the relaxed state that one gets into. The increased blood flow allows more oxygen to the muscles in the body and thus a more efficient break down of the lactic acid. This acid has been know to be the cause for tension and anxiety.
So just sitting down quietly with the spine straight and just following the breath consciously is simple way to meditate.
Source : Meditation from the Tantras - Swami Satyanananda