Needs: Needs are feelings one must have something or do something. It is often connected with one's body: One has needs to breathe, to defecate, to eat, to drink, to sleep etc. Needs are like sensations: They are given to one, and indeed one may say up to a point that needs inform about one's body like sensations inform about one's environment. See desires.
Some needs are natural in the sense one is born with them, and others are acquired by imitation or education or choice. In either case, satisfying a need strongly tends to please, in some way, and a need one has that is not satisfied strongly tends to pain, of some kind.
Moreover, many human natural needs - such as: eating, drinking, sex, defecating - are in fact highly ritualized and subject to many kinds of moral rules that regulate how and when a certain kind of member of a certain society may or should try to satisfy these needs. Indeed, this education, cultification, ritualization and regulation of natural needs seems to be typically human.
Also, many of the feelings that individual human beings feel as strong needs are in fact acquired, cultivated and learned, and may be altered in the future by presently altering some of one's values or one's beliefs.
In short, the "must have" in human needs is conditional, and in part given by and dependent on moral and social norms, and in part given by and dependent on individual human choice or preference.
And if you feel you "need" to do something, nearly always the choice of how and when and if is and remains up to you, and is lost only when you choose to surrender to your emotions.