Working Hard
Some people think working smart is the opposite of working hard. And some others argue it's being lazy.
From my journey, I've learned that neither of the answers paints the picture accurately.
I worked with people who used to grind mindlessly to follow social standards.
I also worked with intelligent people who found a quicker way to do a job but couldn't foresee its long-term consequences.
Then, I worked with some people who seemed lazy on the surface but thought deeply about a process to find sustainable improvements.
Based on my experience, the opposite of working hard is working thoughtfully.