How can a person learn to say "no"?

Saying "no" unskillfully nearly cost me my life.  I was trained to be firm and calm; to repeat "no" as many times as necessary until the boundary was made clear.  "No," they said, "is a complete sentence."  

One of the things we teach, in my job with court-mandated clients, is discipline, and one of the ways we do this is by enforcing punctuality.  On a summer afternoon, 15 minutes into a process group, a young stranger threw open the door and walked in.  

He was short, maybe 5' 1, and pale.  His pants hung low on his hips and, looking back, he was too confident for someone wearing a plaid golf cap too big for his head.  

I asked him to step outside with me - as was company policy - to explain how to attend a make-up activity and send him on his way.  I was half standing when he said, "No. I'm staying."  He was physically in front of the closed door.

"You can come back next week, but I can't allow you to attend today."

"You will let me attend today." 

"No, I can not."

After several long minutes of back and forth I finally said.  "I can't allow you to attend, but I am not going to physically force you out the door.  You will be getting no credit for today. You need to leave."  I sat back down with the group.  "What's a situation in your life when someone wouldn't take 'no' for an answer?" I asked.  

After five more minutes of being ignored he left, and the group continued.  An hour later the group was over and I was standing outside my office talking to a client.  One of the group members came running down the hall, eyes wide. 

"Diane! Don't go outside! He's waiting for you in the parking lot with a gun!"

Long story short, he didn't shoot me or anyone else.  By the time the authorities arrived he was gone.  When we realized he wasn't in my paperwork and the clients who reported him melted away at the mention of the police I started shaking so much I had to sit down.   The officer taking the report said, "People like this make a couple mortal enemies every day.  Lay low for a bit and he'll quickly forget you in his rage at the checker in the grocery store."  I found this equally distressing and comforting.

I went to visit my godparents in the mountains.  I refused the gun they offered when it was time to go home.  I got and still keep big dogs at my house.  For the next several months I scanned the faces of the hundreds of clients I passed in the halls at work.  He showed up occasionally in my dreams, or his hat did at least, because in my memory I still can't see his face.

One of my friends makes me laugh when he says the state motto of Arizona is "An armed society is a polite society."   So, all this to say, here's how I've learned to say no:

"I wish...but..."

"I wish I could let you into group late, but the state law says we can't."

"I wish I could include your ideas in my next workshop, but the curriculum is already worked out."

"I wish that I could lend you $100, but I am short this month."

When things are intense I add "and" to the mix. 

"I wish I could have you stay on my couch, but my home is my refuge and I need my quiet time."

"I wish I could just let you in this one time, but the law is really clear and I'd lose my job."

If it gets emotional or extreme, I load on validation and send them somewhere for more help.

I know, it's awful. You came a long way and the bus was late, and if I could I would SO break the rules for you.  Maybe you can head up to the front office and see about setting up a make up group right after group next week."

"No," some people say, "is a complete sentence."  It is; it's just not always the best sentence for the job.