If you give to others even though you are in need, then you have reached altruism.
Altruism is when a person cares for others’ needs more than his own despite his need. He might stay hungry to feed others and stay thirsty to let others drink.
`A’ishah, the Mother of the Believers said: “Never did Allah’s Messenger fill his stomach for three consecutive days till he passed away. If we wanted, we would have eaten till we felt full, but we prioritize others over ourselves.” (Al-Bayhaqy)
Allah praised the altruistic people, saying:
“They give [them] preference over themselves, even though they are in privation. And whoever is protected from the stinginess of his soul – it is those who will be the successful.” (Al-Hashr 59-9)
Watch this video to know more about altruism in Islam!