Get to a quiet and comfortable place.  Think of a place you have been like for instance a scenery of a river in a forest during a holiday.  Then try to recall in as much detail as possible all that you felt at that time.  Try to hear the sounds of birds and beasts you heard.  Try recalling in the mind the things you saw in detail with colors, contrasts, and shades.  Try and recall the smell.  Try and recall the breeze and how you felt it brushing against your body. Relive the whole experience as you enjoyed it then.