The good you do to-day may be forgotten tomorrow. ...

The good you do to-day may be forgotten tomorrow. People may even say 'Oh, what he has done? Anyone can do what he has done or even he has not done anything.' Interestingly, such talks are made behind your back. You would not know and when you come to know, it might not be worth knowing.
But , does it mean you would stop doing good? No, you will not because it is not in your nature to do bad.