Been in my current role for 5 years and doing okay. The thing I always think of is this set of facts:

1. There is a hard limit of the amount of work you can physically / mentally. Lets say the theoretical limit is like 18 hours a day, 7 days a week.

2. There is a "soft" limit where you as a worker have decided "I have 'enough' work. I will push back on any future asks until some tasks are completed or removed.

3. You more or less decide how close the soft limit is to the hard limit.

4. The closer your soft limit is to your hard limit, the faster you will burn out.

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I really don't why people who are susceptible to burn out don't just move their soft limit up an hour or two a day. If you wait until you are working 9-10 hours 5 days a week before speaking up that you have too much work, or the timeline is not going to happen, why not just do that same thing at 7 hours?

90% of the time, a manager has little to no idea how much effort something takes.