here goes nothing
[American & Australian, informal]
something that you say just before you do something that you think will not be successful.
Well, here goes nothing - let's see if I can pass the driving test.

[TahlilGaran] English Idioms Dictionary ▲

Here goes nothing.
ready to do something but think that it will probably be a waste of time and will probably fail
"Here goes nothing. I have already asked him to lend me some money and he always says no but I'll try again."

[TahlilGaran] English Idioms Dictionary ▲

here goes nothing
interj., informal I am ready to begin, but this will be a waste of time; this will not be anything great; this will probably fail.
■ Used especially before beginning something that takes skill, luck or courage.
"Here goes nothing," said Bill at the beginning of the race.

[TahlilGaran] English Idioms Dictionary ▲