Keep track of your accomplishments as they happen
One thing I’ve been historically terrible at doing is regularly keeping track of my accomplishments while they happen. Day to day all those small things you do which are “just part of the job” seem like they’re no big deal, but for an engineering manager (or any manager), all those little things in aggregate ARE accomplishments. And because they’re smaller they’re naturally much harder to recall later when you need them (eg, reviews, career development, interviews).
So don’t be like old me, be like new me. Think about your career WHILE it’s happening, not after. New me has a weekly reminder and a long running document to force me to write down my accomplishments, no matter how small, and I’m committed to sticking with this. I’ve been at it about a month and the doc is already a full page long!