A "tough" person is someone who is not easily defeated, someone who is resilient or persistent. "Tough" can also mean difficult when applied to a situation (e.g. "It was tough to open the jar because the lid was stuck.") "The going" in this case refers to living through a period of time, so "When the going gets tough" means "When you are living through a difficult time". "To get going" here means to get active in some way. "The tough get going" in this case, then, means "Those who are not easily defeated get active in trying to solve the difficulty". Or: "When living through a difficult time, those who are not easily defeated get active in trying to solve the difficulties, rather than just giving up".

When a situation is difficult or dangerous, strong people work harder to resolve the problem. This saying relies on a difficult play on words; it could be rephrased word-for-word as: “When the situation becomes hard, strong people start working.” This saying is attributed both to Joseph P. Kennedy (1888-1969), father of the USA President John F. Kennedy, and to Norwegian-born American football player and coach Knute Rockne (1888-1931).This motto is typically used in American English but may be used in other varieties of English too. This was also the title song from the soundtrack of the movie The Jewel Of The Nile, starring Michael Douglas, Kathleen Turner and Danny DeVito. Listen to the song http://www.youtube.com/watch?v=fg3vzl_VwLc

"the tough" means the tough people. "the+adj" refers to a group/type of people. "the rich"means "the rich people","the poor"means"the poor people". The sentence means" when it's more and more difficult to do something, people who persist on it move forward". it's telling people to persist on difficulties, and don't quit easily. hope it helps^^

it's an idiom, meaning when things get hard, you (the tough) work harder or fight back.