Some of the happiest times of my life were when I gave up: dropping out of school, quitting a job, ending a dysfunctional relationship, shaving my head rather than fighting my receding hairline. Usually the exact moment was scary (how will I pay rent?), awkward (disappointing my advisor/boss/girlfriend), or depressing (admitting failure). But soon afterward I felt free as a bird and that feeling stayed with me for a long time. In fact, I’m feeling cheerful right now just thinking about not being in those unpleasant situations.
The traditional view is that lazy people give up too soon. Sure, but if you are a responsible, hard-working person then you probably give up too late. If you have repeatedly done your best but a situation is making you miserable then get the hell out. Don’t agonize over sunk costs. That time and money are gone and more suffering won’t bring them back. Don’t worry about looking like a failure. Worrying about what other people think makes you their servant.
I apply this to business all the time, especially in the last five years. I canceled lots of distracting marketing projects and relationships with high maintenance resellers. It was not fun dealing with the disappointed business people, but it was worth it. That freed up time for important activities, like releasing two or three products per year (we used to do only one).
Pare your life down to just the few things you do well and you will find happiness. You will probably be successful too, but I care much more about the happiness.