The thing you call impossible may be the thing you are unwilling to pay for.

Some things are genuinely out of reach, and some are only expensive in a currency you would rather not spend: hours, discomfort, money, a conversation you have been putting off. Calling those impossible closes the discussion in a way that naming the price would not, which is much of the appeal.

Take one thing you have called impossible and write down what it would actually require. You may still decide against it. Declining something knowingly is a different position from being unable.