Ask HN: How do you keep your SWE skills sharp outside of work?

For context I am employed as a SWE and I find my job generally enjoyable but I also feel like I’m not learning any new skills and maybe falling behind the industry. I’m not in a position to look for a new job at the moment but I want to do a little something each day to stay sharp.

What is currently worth focusing on for general longevity in this field?