The way you stand, walk and sit all make a big impression.
Good posture makes you appear taller and slimmer and you will seem more confident and positive.
Hold your head high, keep your back straight and pull your shoulders back. Tread lightly (no clumping, thundering footsteps), and don't drag your feet or shuffle.
How you sit is also very important. Women should keep their knees together when seated (preferably with their ankles crossed). Men should avoid sitting with their legs excessively wide apart, and should never tap their feet or repeatedly jiggle their leg up and down.