I had to check the word "tenacity" and "tenacious" in a dictionary but in that I have a new word in my vocabulary. Coming back to the topic, I think that tenacity is important regardless of century. One has to be tenacious if he want to succeed and accomplish something in his life. For instance, in the business world, the best businessmen usually are very persistent even in the case of a failure. Otherwise they could not get on and make money.
Another example is Thomas Edison who made thousands of experiments before he found a lightbulb. If he had gave up just after his first failure, he would have not been famous today.
For me tenacity is an ability to stand up after a failure notwithstanding how many failures you made before.

Hi!Thank you for creating this post, I really like discussing and writing in English!
I also had to check meanings of these words in a dictionary, but now I think I've already understood them and am ready to discuss.
What is the tenacity... Such a difficult question, I'm not sure if I'm able to explain this meaning even in Polish. I would say it's a quality making people reluctant to change their mind about sth or their dealing, actions. I think it's a quality that a lot of people are born with. Once they decide sth, they don't want to rethink it and once they start doing sth, they are determined to end that. As I see it, 'tenacious' is a synonym to 'stubborn'? Do you guys agree? Or maybe tenacity is u for creating this post, I really like discussing and writing in English!
I also had to check meanings of these words in a dictionary, but now I think I've already understood them and am ready to discuss.
What is the tenacity... Such a difficult question, I'm not sure if I'm able to explain this meaning even in Polish. I would say it's a quality making people reluctant to change their mind about sth or their dealing, actions. I think it's a quality that a lot of people are born with. Once they decide sth, they don't want to rethink it and once they start doing sth, they are determined to end that. As I see it, 'tenacious' is a synonym to 'stubborn'? Do you guys agree? Or maybe tenacity is kind of stubbornness but in a nobility vein? Perhaps tenacious means determined to achieve a goal? Maybe, like a user mniszka said, it's a quality of heroes, people of success? This may also be true. Let me know what you think about it.
Personally, I believe I'm tenacious. I find it uneasy to decide sth but once I do I'm unlikely to change my mind. I am able to work really hard to achieve sth.
Ok, this comment turned out to be quite long, so I guess it's enough ;) Please also comment what you think.