The prevalence of these diseases not only affects millennials' health and lifespan, but also their bank accounts. Those with two concurrent chronic health issues spend five times as much. The average health insurance plan participant without a chronic condition pays just $778 a year out of pocket. Declining health is only one piece of the puzzleWhile older millennials are experiencing higher rates of chronic health conditions, it may not be strictly due to declining health. This was especially important for younger Americans, who were given the option to stay on their parents' health insurance plans until they were 26.