How do you define selfless ? If you google the word selfless, they will define it as
one who is concerned more with the needs and wishes of others than with one's own
Wikipedia on the other hand defines it as -
Selfless in biological organisms can be defined as an individual performing an action which is at a cost to themselves (e.g., pleasure and quality of life, time, probability of survival), but benefits, either directly or indirectly, another third-party individual, without the expectation of reciprocity or compensation for that action.
Almost every religion in this world preaches the mantra of selflessness. There is a famous saying from Geeta - "कर्म करो , फल की चिंता मत करो ।". It simply says do your job without expecting/bothering about the outcome , as outcome is not in your hands.
But is it possible to attain pure selflessness ? According to me, being selfless is extremely selfish. Actually, selflessness is a redundant word. This is because absolute selflessness isn’t even possible. The choice to be “selfless” will always be driven by a form of serving one’s self. No one will chooses to be selfless because they absolutely hate it, rather people choose to be selfless because they want to. If I choose to present an expensive gift to one of my close friends, it doesn't mean I am being selfless. On the other hand, I chose it because it will give me indirect pleasure/happiness in terms of his/her happiness.
The only possible selflessness would be choosing to deny your desires simply because they’re your desires to deny regardless of whether those desires were “selfish” or “selfless”.
IMHO, closest thing to selflessness is mother's love.