Latin Quote

I'm looking for a quote I translated once back in high school.
I think it is from Cicero but I'm not sure.
In essence, it comes down to this:
Never worry! If you have a problem you can solve, don't worry just solve it. If you have a problem you can't solve, why worry you can't solve it anyway.

This quote might have a connection with another quote from Cicero:

“Six mistakes mankind keeps making century after century:
Believing that personal gain is made by crushing others;
Worrying about things that cannot be changed or corrected;
Insisting that a thing is impossible because we cannot accomplish it;
Refusing to set aside trivial preferences;
Neglecting development and refinement of the mind;
Attempting to compel others to believe and live as we do.”
― Marcus Tullius Cicero

But once again', I'm not sure.

I would really like to know where this qoute comes from and the original latin translation.
Does anyone knows this quote or knows another way to find it.

Thanks,