Certain emotions allow the frequency or vibration of the person to rise and remain at a higher level - love, joy, gratitude, for example - while others - boredom, sadness, anger, fear - vibrate at a much slower rate, thus keeping the individual at a lower level of energy. The person who is experiencing these "negative" emotions will have more difficulty with their health. This is not merely speculation. It has been proven and can be substantiated by careful observation. Truly happy and loving individuals are sick far less often than those who are angry and critical.
Watch your feelings and thoughts next time, or review them just as you realize you are feeling unwell. Were your thoughts loving, grateful, happy? Or were you instead dwelling on injustice, plotting revenge or feeling envious of someone? How we feel has a direct correspondence to the life energy flowing freely through out bodies. Feel good and you will! Namaste!