ExcusesExcuses can be a smell in a discussion. You feel you have to give more and more excuses why you can't possibly do X - why? Maybe because the fact that you can't do X is not (yet) acceptable to your dialog partner. If that's the case, it's time to shift gears: Give your partner the alternatives and their consequences ("I can't do X, but I could do y1, y2 or y3...").

This totally changes the situation for your dialog partner: Instead of being forced to accept a non-acceptable answer, he is now empowered to make a decision.

In other words: Present alternatives and their consequences as the basis for a decision, and the perceived need for giving ExcusesExcuses might disappear. --FalkBruegmann