I have been around the world twice, and no matter what country I am in “no” is understood.  It’s an anointed word, and it is a great defense for getting overcommitted.  Not everyone understands the word “no” I’ll give you that.  However after a while they do get the hint. 

There is a way to say “no” that won’t hurt their feelings and won’t get you in over your head.  You have to look at this as putting up fences around your priorities, your vision, your passion.  It helps you keep the main thing, the main thing. 
Let me sleep on it.  My husband (Dave) and I (after a couple of spontaneous purchases) agreed we wouldn’t make on the spot decision for big ticket items. We agreed we would sleep on it, wait a day before we decided. If we still felt like it was something to go ahead with we did.  If the luster was lost before then the deal was off.  Allow this time for you to ask yourself “can I pack another thing in this schedule?”
Guilt doesn’t come from Heaven.  God is not going to make you feel guilty for keeping your family and passion a priority.  Sometimes people doing the tugging and asking don’t understand, it’s okay.  Be diligent when your on border patrol.  Not allowing access to your already tight schedule is just wisdom. 
Ability doesn’t mean yes.  Just because I know how to do it doesn’t mean I should do it. Does it have anything to do with the vision? It’s great that people see the ability in us but as a leader, this will spread you thin.  Why? Because you wouldn’t be a leader if your weren’t well rounded in more than one area. 
A simple thank you will do.  You don’t have to explain yourself.  No, thanks is okay.
Now is not a good time.This lets them know the timing is off and you are willing to help.  Maybe later would be better for both of you.
Don’t negotiate a no to a maybe.  First of all, a quick no is better than a maybe.  When you finally do get back to them, the no is sort of disappointing.  Some people have a hard time taking no as an answer.  What happens next is negotiations.  You now “Well what if we don’t need it for two weeks instead of one.” or “If we address your first concern, will you help then.”  If you no is no then let it be no.

How do you say no? Or is there a way to say no that just frustrates you?