You can think of your job as "They asked me to do X and I'm going to do X and after that the rest of my 40 hours don't matter." Or, "I'm going to do as much as

You can think of your job as "They asked me to do X and I'm going to do X and after that the rest of my 40 hours don't matter." Or, "I'm going to do as much as I possibly can in 40 hours." The healthy answer lies somewhere in the middle. Burning out trying to overdeliver and prove your worth is no better than underdelivering and slacking off. There is a balance. Exceeding your employer's expectations is of course a good thing as a salaried employee. That's how you build a highly successful career. But one of my expectations as a manager is that you manage yourself so you're still around 3-5 years from now and don't need to take a break for mental health reasons.