Richard Nixon was not actually impeached. He resigned from the presidency before he could be impeached. By August 1974, his popularity had sunk to such a low level, it was only a matter of time before he was impeached and he would have lost any impeachment trial.
Richard Nixon was deeply depressed after his resignation. They did not put him on a suicide watch, but he kept an extremely low profile for more than two years. He did agree to let David Frost conduct a lengthy series of interviews in late 1976 and early 1977. These Frost-Nixon interviews were edited into four, ninety minute television programs that were broadcast in May 1977. They were watched by more than 45 million viewers and a Gallup poll taken shortly afterwards show they did nothing to rehabilitate Nixon's image with the general public. However, they did convince Nixon to reenter the fray as a political pundit and commentator on international affairs. Nixon also wrote nine books between 1978 and 1994 that further burnished his credentials as an elder statesman. After 1980, Nixon was a frequent guest on Sunday Morning political television talk shows, but Nixon pretty much limited himself to talking about foreign affairs.