Any job worth doing is worth doing well.
Any job with acceptable compensation (be it monetary, spiritual, emotional or other) is worth doing.
Any job I take on will have acceptable compensation. (I don’t intentionally commit myself to things that I know I will hate doing and gain no form of reward from.)
So, by the transitive property, any job I take on is worth doing well.
If you live your life by these simple rules, it is possible that you might have a job that sucks, but you should never suck at your job. If you find yourself being terrible at your job, you either need to find a way to be better at it or find a job that is a better fit. By knowingly, willingly being terrible at your job, you are choosing to make your own life worse and having a negative impact on everyone you interact with. Conversely, by doing your job well, you will have a positive impact on the people you interact with, and that, in turn, has a chance of making you feel that your job doesn’t suck.