Making an effort in general (in all things: dressing well, speaking well, working hard) is almost completely a social activity. If there's nobody to impress, it's 10x harder to motivate myself. You end up having to imagine a hypothetical future person that your effort would impress, which is much less convincing to the lizard brain.
In addition to those, having clues that my work is appreciated (by colleagues / customers / users) plays a big role as well.