"... I believe an authentic old man ...."

… I believe an authentic old man would be honest with himself about how much fully conscious and rational life he has left.  He would want to use that time in the best and most appropriate way.  I also suspect he might sense that this stage of life offers meaningful possibilities that were never before available to him.

Daniel Klein

"Make the most of your regrets ...."

Make the most of your regrets; never smother your sorrow, but tend and cherish it till it comes to have a separate and integral interest.  To regret deeply is to live afresh.

Henry D Thoreau

"Life has carried some men ...."

Life has carried some men with the greatest rapidity to the harbor, the harbor they were bound to reach even if they tarried on the way, while others it has fretted and harassed.  To such a life, as you are aware, one should not always cling.  For mere living is not a good, but living well is.  Accordingly, the wise man will live as long as he ought, not as long as he can … He always reflects concerning the quality, not the quantity, of his life.  As soon as there are many events in his life that give him trouble and disturb his peace of mind, he sets himself free. … For no man can lose very much when but a driblet remains.  It is not a question of dying earlier or later, but of dying well or ill.  And dying well means escape from the danger of living ill.

Seneca

"Accept everything about yourself ...."

Accept everything about yourself – I mean everything; you are you and that is the beginning and the end – no apologies, no regrets.

Clark Moustakas