Hans found stress as a physiological coping mechanism due to a fixed event. Negative stimulus results in the body responding physiologically such as an increased heart rate, mobilization of glucose into the bloodstream, release of adrenaline and more rapid breathing. Although Richard Lazarus, he researched this further and described it as a more dynamic process. He called it the transactional theory of stress and coping.
The problem with Hans’s Theory is that it assumes that all change will result in stress response and we know that this is not true. It also assumes that a particular life event will affect the whole population in the same way. We also know that this is not true because some people seem to be more resilient than other people. You also assumed that stress will always cause an illness which is also not supported by new research.
Richard Lazarus however does take into account systems that explain why stress affects different people differently. He takes into account factors such as prior learning, environment, support that works, personality, and individual body makeup.