grammar - Using a present tense verb in an "if" clause, followed by the main clause

Is it possible to have a present tense verb in a sentence like this:

If you resign now, you'd feel sorry later.

Or must you always follow the second conditional format, arriving at a sentence like this:

If you resigned now, you'd feel sorry later.

My goal is not to necessarily to produce a second conditional sentence, but rather to see whether the first sentence is acceptable, whether interpreted as a second conditional or not. It seems acceptable; what explanation is there for this?