Need?! You mean give everything? If I don't have any money, I'll still have to give charity?!
Need, yes.
Charity is different from throwing away, or giving for your own benefit.
If you give away something you do not need, it's simply throwing it away, instead of into a bin, into someone's hands. That is not the essence of charity. Charity is directly linked to compassion, and sacrifice, though people use the name to hide the aims of their actions. They give with the intention of obtaining more. "Give an egg, and take back the chicken."
But that is not helping. Because charity is altruistic, selfless. If you keep giving, and take back more, you would not have made the recipient's situation better, but worse. The poor is giving then. And the rich is simply taking and taking, till the poor completely dry out.
You give what you yourself need. Then you are sacrificing. Then you feel the pain of others. And then do you give more. Your action is pure, because it's selfless. You ask not when you give. Like Kahlil Gibran says: "It is when you give of yourself that you truly give."
You need time, you give some to the poor children who lack affection and attention. You give your own pack of lunch, that's charity. You give your clothes that are dear to you, that is charity. Charity is not only money. Normally, people give away that proportion of their money which is insignificant to their real incomes. Give more, of what you really need, that is charity.
Giving is an art, as some said. Simple reasoning, because artists use their hands to speak out their heart. That is charity.