One day the doctor says "you have developed diabetes", i.e. too much glucose (sugar) in our blood. Why? Because besides diet the only key variable we can control is our weight. Our body fat cells demand glucose - the more cells the higher the demand. The key is to lower the demand i.e. our weight to a level that is compatible with the level of insulin the pancreas can deliver.
Simple? If it is so simple why do we have an epidemic of diabetes among young and old? We are unaware that our body has become less efficient and our eating habits have not adjusted to balance the supply of insulin with a lower demand by our body's cells - i.e., a lower weight. Losing weight is not easy or fun so we ignore it. We choose our palate over our lifestyle.
We can't retire with a guaranteed lifetime income for the same reason. We are unaware that we must guarantee our income throughout our final 30 - 40 year retirement years and we have not adjusted our financial focus to guaranteeing our life sustaining income - risk free - our primary focus has been to accumulate capital. Accumulation stems from our need for financial security. Risk is distateful so we ignore or deny it as a factor in both our mortality and our morbitity.
In the case of diabetes our denial results in building up too much glucose without being aware of it. One day our financial 'physician' informs us that we will run out of income - prematurely. What we don't measure can disable us - physically or financially.