There are several types of offerings, and each culture in this forum regarded them differently depending on their context and incentive.
A regularly scheduled ritual sacrifice, for example, was done on designated days to appease the deity. There may be no reason for doing so other than it is the day dedicated to the deity, and to not sacrifice could anger him or her. Commonly these sacrifices are done by the religious institution. In some examples, such as Mesoamerica, the royalty's blood sacrifice was considered the highest and richest form of offering, so bloodlettings from the nobility were regular. "Going through the motions" is strongest in this case; it's not a case of desire, it has to be done to ensure survival.
A votive offering would be given to not only appease but with the expectation of reward. In giving of yourself, you hope to be given in return. A common votive offering today is tossing a penny into a fountain to make a wish, for example. Votive offerings not only include material goods but also actions taken in their name. Curse tablets in classical religion, for example, were bought or made and offered with the expectation of an action taken against the target. Malice could easily be in your heart, and you would hope the god recognized your offering to project that malice.
A thank offering, sometimes connected to a tithe, is a portion of goods set aside for the deity. There is no expectation of return, but is the person's way of expressing gratefulness beyond mere words, to give of his material bounty. The most generous of spirit could be an unscheduled tithe, but recorded instances of this, giving to the deity at an unprescribed time and without duty or desire for reward, is rare.
Sometimes sacrifice doesn't take the form of goods but duty. In the Incan religion, for example, the temple grounds had a plot of sacred land dedicated to the god, the food from which supplied the priesthood. It was every commoner's family's duty to farm the land for a certain period of time every year as an act of devotion. This was considered very good will, donation of time as well as wealth, and was one of a commoner's greatest opportunities to serve the gods other than being sacrificed.
Naturally, most of the material goods from the sacrifices became the property of the religious institution, unless they were destroyed in offering, such as burning, burying or drowning. It was most likely up to the priesthood to determine whether the generosity of one's offering indicated their level of devotion.
