Sometimes you are not focused because deep inside, you know that the task at hand is not what you need. If this is the case, and you can admit it, then it is an excellent opportunity to reflect on yourself. Maybe you are at a meaningless job, and it is time to move on.
I just want to make a point that lack of focus may not be a bad thing.
I hesitate to give people this advice because most jobs have some meaningless tasks. If everyone who has a task like this would leave his job, no one will stay at his job for a few months. But I deeply understand what you mean.
The unfortunately reality is that most office workers, even tech ones, are so alienated from the results of their labor that it is easy to rationalize their jobs as meaningless.
I'm working on stuff I find deeply meaningful and yet I still struggle with focus and motivation. Working on things that are meaningful and inspiring is an important foundation, but there will always be tedious parts to meaningful work, and burnout can strike any project. The most helpful things I've found is to work alongside others if possible, to take care of your health, to switch things up periodically, and recognizing that getting just a few hours of work done a day is actually pretty good.
