I’ve heard this all my life. While it is true that no one but God is good (Mark 10:18), I believe that people, for the most part, *try* to be good. Consider, that with the same amount of effort you can poke someone in the eye or shake their hand. Most people choose to shake hands. People have the capacity to do much more harm than good using the same amount of energy, yet most people exert quite a lot of energy toward (at least) not hurting others. Even with words, consider how carefully most people craft their sentences to be as “tactful” as possible to spare the feelings of others. It would be far easier to just blurt out whatever we were thinking. Sure, we want to avoid negative consequences but I think, at least in part, that people actually care about each other’s feelings. This is the very basis of the Golden Rule. We are all self-serving to some extent but deep down, most of us want other people to be happy. There are exceptions, of course, such as sociopaths – then all bets are off.
Do you give or help as anonymously as possible? Do you do things for others who you know can not or will not do anything for you in return? Then, I think you are at least trying to be good for it’s own sake. That’s the best any of us can do.