do something that are good to urself

There is a common nature for the Mankind ---selfish,and never considerate others feeling,so one day u are great to everyone,they will think u are week,evern they will guess u are afraid of them,they don't care ur so called kind and friendly.there is an old word in china:Every man for himself, and the devil takes the hindmost.
it's really good,when u walk into the society,u will find someone take care of u,some like u,someone help u,at fact,some goal to u.so don't be easy to trust someone,ever never regard them as friends,real friend just only exit ur middle school,or university,in this society,there is only benifit.