“I haven’t been to Argentina”

is only one word different than:

“I haven’t been to Argentina yet.”

But there is a huge difference in the attitude that the two sentences project.

The insertion of “yet” in the second version keeps the future alive.  “Yet” makes a current statement conditional.  It is subject to change, not absolute.

Try it yourself.  Change “I don’t have a good car.” to “I don’t have a good car yet”  Change “I can’t beat Bill E. at Word for Friends” to “I can’t beat Bill E at WFF yet.”

In Spanish yet is aun and not yet is aun no.  “I don’t speak Spanish aun.” is better than “I don’t speak Spanish.”

This really is a case of “first you do it, then you feel it.”  If you will consciously try inserting “Yet” into statements you are likely to become more optimistic and happier.