When you look good you feel good. For me it has very little to do with you it first of all has to do with my business and as a very high end jewelry designer I must always look well dressed. Secondly, if I am down or depressed, putting on a nice dress or outfit helps put a little extra swing in my stride but thats just me...
Edited to say that also if I am well dressed it significantly reduces my chances of getting fucked with by pigs