Soni2006 has put forward a good case for the physical environment and how it affects our energy levels. It does more than this, of course. It affects our psychological behaviour as well. You can witness this yourself when you simply move from one physical environment to another and find yourself 'role playing' in different circumstances. For example: you can be the 'macho man' when drinking beer with your mates, the loving father when with your little children, the flirt, the speculator, the mentor - there being virtually lots of roles we play subject to the environment we're in at the time.