The majority of my days tend to be not-busy.  I'm what most would term a "production" DBA, so it falls on me to make sure the servers are running OK, the OS and SQL is patched, help the devs and app-owners occasionally with troubleshooting problems, checking that backups ran successfully (even though I don't {currently} control the backups,) and generally trying to stay on top of what's coming up in terms of updates that might bite my servers (the Intel CPU bug that's come up recently is a good example.)

Once every quarter, I need to apply our organizations current Security Technical Implementation Guideline (STIG,) although for about the last year that's been little more than "nothing other than wording changes."  Plus, by getting this done when a server is initially stood up, well, then it's just find the checks that have changed, does the change require me to do anything or did they just shuffle around the wording, and apply or make a note.

Every couple of years, we get mandated to migrate to a new OS (based on when MS ends support, so we just went from Server 2008R2 to Server 2012R2,) and typically at that time I'll make the jump to the current version of SQL (we just went from SQL 2008R2 to SQL 2014, 2017 wasn't released when I started.)  So those are always a fun, busy couple months.

What with some issues getting tools on the devs PCs, I've started helping out some with SSIS packages that people need, which is actually kind of fun.