Decide whether to say yes to a favour someone is asking of you right now

Someone wants an answer in the next five minutes and you are still weighing it up in your head, going round in circles. This forces a decision: yes, no, or yes with a condition, plus the one reason that actually matters, so you can reply and move on instead of stewing over it all evening.

Help me decide whether to agree to a favour or request. Here is what is being asked: [describe the request]. Here is what saying yes would cost me in time, energy or money, and here is what saying no risks, socially or practically: [add both]. Give me a straight answer: yes, no, or yes with a condition, in one sentence, followed by the single strongest reason for that answer. Do not hedge or give me both sides at length, I need a decision I can act on in the next five minutes.