Just because you're not doing all you could be doing doesn't mean you are negligent. "You're not being all you could be" is neither a sin nor a crime, and sometimes it is really not worth it. A lot of people think they would be happy if they had just a little bit more, or if they could do something they were not doing. And I know a lot of people who are really stressed out because they felt they were never enough.
Being able to weigh cost versus benefit is an essential ability when you are deciding how far up the ladder you will climb. And it's usually possible to climb far enough to be really unhappy.