"That's not shallow enough, you wouldn't die", I said to the man who was willing to jump off the cliff. He turned and looked at me. Do you really want to die? Then you may not die if you jump right over that place. The last time I jumped right off that cliff, I was able to stay alive until the rescue team came and got me out. So you see, you really may not be able to achieve your dream if you jump right off that cliff. I think you need to find a better location to jump so you can peacefully die.
My first statement alone is enough to stop anyone in his tracks who is trying to kill himself. He would expect me to be sympathetic and seeing that I'm not, he would relax, listen to me give him tips on dying faster and peacefully.
By the time I'm done making the second statement, I'm pretty sure he would have withdrawn his decision to jump off and in his mind, making other plans for a good location.
It is at this time that I will talk to him about why he shouldn't die compared to why he wants to die. I'm a very good motivational speaker and I am quite sure that if I can stop anyone in his tracks from killing himself, then I can as well talk him out of it entirely.