“Tough times” is one of the polarities of a given situation by the humans. Every human has his own unique thumbprint to his or her judgment capabilities and no two judgments of the theoretical situations can be the same.
“Tough people” is one of the polarities of the judgment of the result or outcome of what a person goes through a single or series of events. However there is no accurate measurement to quantify the situations or the ability of the humans who undergo the situations and neither the observer, hence a persons qualifying criteria is an approximate validation on the approximate requirements.
The nature of the statement is strongly false and highly random in nature, and is use widely in contemplating to be hypothetically Tough, or be emotionally charged to be prepared to the fore coming situations in order to produces the expected event or events that is to be tough.
This statement can also be interpreted as survival to the fittest, people who survive are the people who have master the skills of the ability to adopt and adaptation, hence any given situation if a person is able to survive he can be proclaimed to be survivor or according to the quote, tough people.