I noticed a huge number of benefits, but one of the most surprising was that it forced me to confront a number of difficult decisions.
There were a few times in which I was bored (waiting at the passport office, sitting on a plane) in which I started to think about decisions I had to make that were very difficult in ways that caused me anxiety: firing a person I'm good friends with, shutting down a company, stuff like that.
I realized that ordinarily I would simply refuse to engage with the decision: I'd get on my phone or "get busy" somehow and so simply postpone thinking about the issue indefinitely.
But when you're stuck at the passport office for 2 hours with nothing to do, you can't but help think about the thing that is top of mind, anxiety be damned.
For someone that is prone to anxiety around certain topics (conflict avoidance, "disappointing" people, etc) having times in which I was forced to engage with the topic had truly enormous benefits.