I would stick to the option given by Marcelo. It says it all.
[no pun intended ]
Now, I will let you know some little things about English that maybe will be handy to you in the future.
Sometimes they have the habit of using suffixes (here -ess-less-ness, etc...) to morph one noun into an adjective, as in:
"useful" (útil) usefulness (utilidade) and so on and so forth.
So, "in a certain way" we could say that the author used that "literary device" and a bit of poetical licence (or "stretched the point" if you wish), so "get to it" (chegar - ao sucesso claro.) would turn into
get-to-it-ness (but then, would have a very strange sound) so he changed to
get-to-it-vness (but then, there would be the morpheme, the sound of "i" anyway, and the case for separation of syllables that would need the vowel; then the third iteraction that ends...this way...)
get-to-it-iviness ("chegabilidade", except that is untranslatable into Portuguese this way, the closer meaning to it would be "atingibilidade
Now, with the above reasoning, things get easier. So, "stick-to-it-iviness" would be (in a meaning closer to Portuguese and with the above suffix rule-of-thumb): estabilidade
/permanência/ (no sucesso, uma vez conquistado).
Just a grammar point here; in practice you can see that it means the same as Marcelo has pointed out.
But I took the liberty of presenting the topic of suffix, perhaps it was interesting for you.