Actually I call it having a “mid-life awakening”. It’s the moment one realizes that they have more years (behind them) than they do (ahead of them). Each person has their own “trigger” and everyone reacts differently. Some people choose to live their life with reckless abandonment. Others do some serious introspective thinking and soul searching to determine what it is they want to accomplish before they transition and create (Bucket lists), while others fall into deep despair. Those people that believe in a “higher power or God” and a “afterlife” tend to take things more in stride.
Generally speaking it’s the individual’s family and close friends that have a difficult time adjusting to the person’s “new lease on life.” Awhile back I wrote a hub expressing more of my opinion on this subject matter. https://hubpages.com/health/makethemostoutoflife...
As for solutions the only rational thing to do is (accept the fact) that no one lives forever including yourself. One exercise is to write your own obituary and then set about accomplishing the things you want said about you. Last but not least you want to make the most of each day while at the same time enjoying each moment.
“Worry does not empty tomorrow of its sorrow. It empties today of its strength” - Corrie Ten Boom