Meaning: If you keep trying, you will eventually overcome any challenge.
Choice of Words: Never gave up means to continue trying even when it is difficult. Tough means difficult or challenging.
Meaning: This sentence means the same as the first sentence, but it uses different words.
Choice of Words: The word "persisted" means to continue doing something even when it is difficult. The word "challenging" means difficult or hard.
Meaning: This sentence also means the same as the first sentence, but it uses different words.
Choice of Words: The word "quit" means to stop doing something. The word "difficult" means hard or challenging.