What an original thought, OP...
“Our sires’ age was worse than our grandsires’. We, their sons, are more worthless than they; so in our turn we shall give the world a progeny yet more corrupt.”
Book III of Odes, Horace
circa 20 BC
“Whither are the manly vigour and athletic appearance of our forefathers flown? Can these be their legitimate heirs? Surely, no; a race of effeminate, self-admiring, emaciated fribbles can never have descended in a direct line from the heroes of Potiers and Agincourt…”
Letter in Town and Country magazine republished in Paris Fashion: A Cultural History
1771
“Never has youth been exposed to such dangers of both perversion and arrest as in our own land and day. Increasing urban life with its temptations, prematurities, sedentary occupations, and passive stimuli just when an active life is most needed, early emancipation and a lessening sense for both duty and discipline…”
The Psychology of Adolescence, Granville Stanley Hall
1904
“Parents themselves were often the cause of many difficulties. They frequently failed in their obvious duty to teach self-control and discipline to their own children.”
Problems of Young People, Leeds Mercury
1938
“…in youth clubs were young people who would not take part in boxing, wrestling or similar exercises which did not appeal to them. The ‘tough guy’ of the films made some appeal but when it came to something that led to physical strain or risk they would not take it.”
Young People Who Spend Too Much, Dundee Evening Telegraph
1945