in life we always have a choice to think either positive or negative, some people choose negative and soon it becomes a habit and the result is called depression. contrary to that some people choose always to think positive irrespective of the situation. they make thinking positive as a habit and these people whatever life throws at them they always happy, successful etc. i think this is the greatest lesson all humans need to be taught from early age. yes choose the second. make thinking positive and becoming productive as a habit, refuse to think in negative way even if the situation is so challenging.
what you think in your mind is what you are. if you think positive your life will be positive, if you think negative everything gets negative, life becomes so depressing etc. to give proof of it consider our mood after seeing a sad movie. also consider our mood after seeing a cheerful movie, also consider our mood after seeing an erotic movie. yes these all influence our mood for some time. so think what will happen if we think positive all the time. so every time you get urge to think negative remind of this basic fact and refuse to let those negative thoughts come to your mind.