A previous job of mine was being the guy who was flown out to a tour to fix problems with lighting. I learnt the value of the word “no”. It normally revolved around a couple of hours till doors, trying to fix stuff, and giving options such as, “I can give you A and C or B and C, but I can’t give you A, B and C”.
No is the hardest word of all to say, but when you use it, people tend to give you more respect than saying yes, knowing you can’t deliver, but it was what the person asking wanted to hear.