When one attempts to keep their emotions inside, not acknowledging them or sharing them out loud with another person, these emotions build up internal energy.
The example of a tea kettle with slowly boiling water inside is frequently used to demonstrate this concept. As more grief-producing events occur, the emotional energy builds - like turning up the fire under the tea kettle. This emotional energy needs to go somewhere to be dissipated. Often this happens with changes in behavior: crying, shouting, fighting, using STERBS, isolating, etc. In addition, this pent-up energy can result in ill health effects, including high blood pressure, headaches, bowel symptoms, and other bodily effects.
The question is asked, “Would you rather be a storage tank or a processing plant for this emotional energy?” The answer, of course, is that it is healthier to process it rather than store it - counter to what society teaches us from a young age.