In almost all cases the candidates held other offices. They simply go back to their old job if it is still there. Several also have college degrees that allow them to work in their degree profession. For example John McCain is a US senator and Sara Palin is the Govenor of Alaska, both still can hold these posts. Some are lawyers, which go back to practicing.
Losing candidates just go on with their lives. Some go back to their old jobs. Some find new jobs. Most of the major candidates get new offers for positions either in government or in business. Some run for office again and some already had an office which they did not resign when they ran or even ran for another office at the same time.
go home take 2 aspirins, and go to bed
If the incumbent loses the election, they usually stay until January of the following year until the elected candidate takes office. If the losing candidate is not the incumbent, the losing candidate, just, goes, home!
No candidate loses until the ballots are counted. How can you be certain that a candidate is a "losing candidate" before the election is held?
De Witt Clinton in the 1812 re election.
Charles Pinckney in the 1808 Presidential election
Rufus King in the 1816 Presidential election
Aaron Burr in 1800 Presidential election
Thomas Jefferson in 1796 Presidential election
Thomas Dewey of New York was the losing Republican candidate in 1948.
Thomas Dewey of New York was the losing Republican candidate in 1948 against Truman.
The losing candidate gives a concession speech.
What candidate and party did Fillmore support in the 1864 election
Ross Perot was the Reform Party candidate in the 1996 presidential election.