Engaging in activities that require mental effort, like listening to new ideas, can deplete body budgets but does not indicate a problem, only the need to replenish energy. Stressful situations, inadequate sleep, unhealthy eating, lack of exercise, or excessive social media usage can lead to brain preparing for battles unnecessarily, causing a drain on body budgets. Uncertainty and ambiguity, such as experienced during the COVID pandemic, can significantly deplete body budgets, leading to anxiety and depression. Continuous depletion of body budgets over time due to inadequate replenishment can result in physical illness in adulthood. Studies indicate that adverse childhood experiences can compromise the immune system, making individuals more susceptible to illnesses, showing that illness is a result of a combination of virus exposure and a compromised immune system, with childhood experiences being a significant predictor of health outcomes.