The first and foremost fact we must acquaint ourselves with is that certain emotions are appropriate given a stimulus and certain others are not. See CS Lewis for a detailed and robust argument in Abolition of Man. For now a few common sense observations will suffice. Seeing a baby and feeling happiness, tenderness, affection, and care is appropriate, "fitting," natural, normal and good. Seeing a dead rat in the basement and feeling disgust is also appropriate. Similarly, receiving a gift has an appropriate emotional response, that of thanksgiving, humility, and gratitude.