(Posting by request.)
Burnout and Impostor Syndrome will happen several times in a security career. While many ask about how to overcome it, the real question is why does this happen?
IMO, the main reason is we have very demotivational work in a misunderstood field. Our field is powered by negativity, justified with skepticism, and influenced by those who don't work with us on a daily basis.
We stop bad things from happening. An exciting day at work usually involves a crime, e.g., the organization we've been tasked with defending was attacked. A good day usually means our designs worked, but nobody noticed because they were able to do their jobs.
Breaches are happening everywhere and nobody seems to get punished effectively for it. In fact, some get jobs - by the very government asking us to defend better - because of it.
Tech is evolving faster than any other field, innovative companies are trying to adopt it a few months after initial release, and we need to be at least 3 months ahead of it, which means researching beta releases and conceiving the guardrails for something that may not even be a thing.
On a personal relations level, we're not a fun group to work with. People don't like dealing with password changes, MFA, firewall rules that block them from uploading files to customers, mandatory email encryption, etc. because we get in their way.
Audits ain't fun: It's not what you did, it's what you can prove you did. You have to back up every claim with documentation, logs, etc., that you typically don't think about unless you've failed an audit before. The auditors rarely know the ins and outs of how much effort it takes to meet compliance (regardless of what some will say, it is not easy) and they've got the ear of the BoD.
Finally, there's the cost. Breaches are expensive, so we're expensive. It's not difficult to see why the CFO scrutinizes our expenses when there's not any revenue coming in from the cyber folks. As messed up as it sounds in this forum, it makes financial sense to weigh "how much would the ransom cost?" vs. "how much do these 4 technologies to mitigate ransomware risk cost?"
When we get out of our rhythm and look at our own situation it's easy to stare off and ask "why do I bother doing this?" ...and that's when the burnout starts.
So how do we counteract the above? By remembering the reason we wanted to do this in the first place. FIND YOUR WHY (supporting your family? being on the edge of tech? protecting people?), print it, and use it for motivation.
And, for the love of all things holy, have a sense of humor about it. Laugh or you'll cry.
The Simpsons did exactly that in "And Maggie Makes Three."