A generous person understands that not every need is theirs to solve.

You will encounter more need than you can meet, and treating all of it as your responsibility ends in exhaustion and resentment. Choosing where you give is not coldness; it is the only way to give anything sustainably rather than spreading yourself into uselessness.

Decide in advance where your effort goes, so you are not deciding under pressure every time. That makes the yes wholehearted and the no clean, and it saves you from the guilt of not being able to do everything.