It also helps to never give 100% at work, more like 60-80% so the baseline is set. Then when things get stressful you can temporarily put in 100% capacity and shine without actually suffering much.

I can't work consistently. There are days I do nothing and others I catch up with the work of multiple days. To cover it up, I usually take over urgent tasks and "could anyone..." kind of things that come up so it looks like I'm always engaged and motivated.

Thinking about it - maybe I'm not doing nothing. I guess I just found a way to work around my shortcomings while still looking busy and helpful most of the time. At least I've never had anyone complain to/about me that I don't do enough in the past 5 years.