2. Because even if one relationship, job, or cause is doomed to failure, you can find something else with a chance of success.
3. Because chances are you could be more successful if you tried a slightly different approach.
4. Because you have quiet cheerleaders all around you who believe in you and want you to succeed.
5. Because when good people give up, bad people gain power by default. And everybody suffers in the end.
* All opinions my own. Photo (by me) is of the cover of Entertainment Weekly, 4-11-2014 edition.