e.g.: I’ve half a mind to quit my job right here and now -- only if I'm already set for life, that is...
or: I’ve a good mind to quit my job right here and now -- only if I'm already set for life, that is...
This English expression is used in a rather disapproving, threatening tone, even if half-jokingly, when you are faced with something unpleasant. It also implies that you are not likely to follow through with the threat you've made or whatever action you just said you were going to do, after all.
How is this idea commonly/idiomatically expressed in Russian? I asked around, but it seems the expression cannot be easily rendered in Russian.