Busy usually means your day got stolen by other people's problems. The fix: write three priorities on paper each morning, keep it visible, and check at 5 PM if you actually did them. If not, you picked the wrong tasks.
If you get to Friday and you genuinely can't remember what you actually achieved this week, you don't have yourself a productivity problem. The real problem is that by 11:00 AM on most days, the day already belongs to absolutely everyone else. You've answered 6 messages, you solved 2 problems that weren't yours, and the thing you actually needed to do is still sitting there untouched. Again, and that is not a busy day, that's a stolen day. To fix it, write down your 3 big things on paper, not on your phone. Keep the list visible all day long, and at 5 PM, just tick off what's done. If nothing is ticked, then you picked the wrong 3, and that feedback is the whole point.
