I did the data entry job for (as I recall) about a year and a half: it paid the bills and gave me a better life than I would have without it and I didn't have the right qualifications or work experience for anything better. For those reasons I was appreciative of the work while at the same time I looked to improve my working situation... something I can say of my work today (though what counts as improvement in working situation is way different now).
There are many jobs out there that need doing. Many of them are boring, or dirty, or dangerous. I don't think that necessarily makes for any more or less of a "sad life". I'm completely thankful to those that do those boring, dirty, or dangerous jobs. Some of them, like me, did it as an early first job sort of thing and used the work experience to get a better job: we paid our dues as it were. Others, like what I find unfulfilling or uninteresting. Some want to work outside, some want to work with their hands, some want to work with minds, and some simply want to be a bit financially better off than they are without the work.
"There is no such thing as a lousy job - only lousy men who don't care to do it."