Write your to do list and you will soon want to burn it and have a drink.
I can use time effectively by making sure I split my worrying load into 2: projects vs tasks.
I instinctively know what my projects are so I make time count by demolishing as many tasks as possible. Some are obviously longer than others but I accept that I am unlikely to focus properly on the big tasks if I have another 20 hanging over me.
So I start with the quick wins, the ones I can do quickly or delegate. I am not focusing on the task themselves but am focused on reducing the number of tasks. If I halve my tasks, this is the first win of the day.
Then comes the longer tasks. I actually schedule them in my diary. This gives me space in my head and reduces the pressure. If there is no room in my diary for this work, I am obviously going for a kicking at any rate so now is a good time to know and to come with plan B.
Then it is a question of following the order of the tasks in the diary which, of course, never happens because of constant disruptions. But at least at this stage I can move tasks around, reduce time allocated to them and maybe review the scope of the work, I always plan on outstanding but in real life, good enough is good enough. Others call it fit for purpose!