People can get complacent in their jobs. You may like the work and be very good at it but fall into a rut in which you perform well enough but aren't advancing your career.
Sometimes that's a good thing -- if you have young kids or nonwork priorities, having a job you can do well easily can be a blessing. In other scenarios, you can end up with a stalled career when you didn't mean to. That can be fixed if you're willing to put the work in.
