I didn't use to track my work and I noticed that at yearly review time it's been pretty difficult to remind what I actually did for last year. I'd go through merged PRs in the main projects, but it's only a tip of the iceberg.

Some time ago we moved daily standup to Slack, and since then I have a pretty good history of what I did each day. I created a wiki page where every 1-3 months I try to summarize all the stuff I did in the quarter (code shipped, dashboards created, docs written & non code work done, like helping X ship Y -- with screenshots, links etc.) and then it gives me a bit of confidence boost during the perf review time.