The realization that you are beset by current circumstances and that you will never now be that premier league player, tennis ace, world champ Down hill rider.
That the best you can look forward to is just more of the same, with a huge dose of apathy, born of the familiarity with the annonymous existense of those harnessed into the rat race.
While also aware that in later years you face the vastness of eternity knowing that you will one day disappear as did all those who have gone before you.
Black Cloud anyone ?.
Anyway. How old do you have to be to be Middle aged ?, and is it the same age for both both sexes ??.