Having trouble with focus? Put the big rocks on your calendar first.
Before you allow yourself or anyone else to schedule meetings on your calendar, block off chunks of time that you'll spend doing deep work. For example, you'll spend Wednesday from 10 a.m. to 12:30 p.m. improving your resume/CV.
If you let others dictate your agenda, or if you plan short meetings, calls, etc. all throughout your day, you're not likely to have a few hours straight to really dig into a tough task, to focus.
After you put the big rocks in your time "jar", you can add the pebbles: meetings, calls, coffee chats, administrative tasks, office birthday celebrations, grocery trips...
It's not trivial to start using this approach. When I see a long to-do list I'm tempted to do lots of little tasks just to shrink the list.
But in the end, scheduling the big rocks first (i.e. making sure you do the deep work) is more productive and less stressful.