I think the how questions you ask are constructive, but the answers will vary in accordance with where you are and your life situation. Very generically, I think the best answer will be " To try to be an asset and not a liability to your friends, family, neighbors and society at large." Now one clearly has different inborn talents and circumstances throughout life will vary widely, so everyone will...sometime or the other...need support from people, close kin and society during times of duress. But when circumstances are better, trying to be a support to others and being constructive in your actions and words goes a long way.
The problem I think is that, due to various capitalistic pressures for promoting a consumption driven economy, we are being bombarded with messages that one is truly worthy in society if we buy that next cadilac car or the next private jet etc. or collect that limited edition perfume, or have that youth enhancing facelift. And if you can't afford it, no worries, there is this nice loan you can get with zero background check. Society has fallen into a hedonist trap, where, instead of accumulating utility to develop long-term social assets, we are being encouraged to fritter away utility into pleasure creating consumables (which also includes facebook, twitter etc. because time is one of the most valuable utility).
