If you've ever helped prevent a suicide attempt, you've almost certainly saved the person's life for ever:

Dr. Seiden’s study, “Where Are They Now?”, published in 1978, followed up on five hundred and fifteen people who were prevented from attempting suicide at [San Fransico's Golden Gate] bridge between 1937 and 1971. After, on average, more than twenty-six years, ninety-four per cent of the would-be suicides were either still alive or had died of natural causes. “The findings confirm previous observations that suicidal behavior is crisis-oriented and acute in nature,” Seiden concluded; if you can get a suicidal person through his crisis—Seiden put the high-risk period at ninety days—chances are extremely good that he won’t kill himself later.

The New Yorker, 'Jumpers'