Train your brain to rein in these distracting thoughts and focus on one thing at a time. Write the wandering thoughts on a sheet of paper (or on notes on your phone or computer) and let them go until another time. Make a to-do list with prioritized order. Then go do what your most pressing priority is on your schedule. Let the other thoughts go and realize you have carved time for them later.
If you have 2 or more top priorities, pick one (if you can’t figure the most urgent, just pick one) and work on it. If you just freeze because you can’t pick one, then none of them will get done. Just start on one task, then focus on that one thing and concentrate on only that task. You might put an alarm on with the time you work on one thing and then another alarm in a few hours to work on next task, if you have more than one top priority. Then you spend an amount of quality, focused time on each. Get done what needs to be done by a deadline. You need to schedule your time out so you can knock the work out. Then focus on only that task until you know when you need to switch to another task.
It is good for your brain to think – but rein the thoughts in by writing them down to look at later. The main goal is to do a task every time slot you allotted, without letting yourself get distracted. Concentrate on only one thing to get done or done to a point, then move on to next task but put all your concentration into it. Train your brain to focus on one thing at a time.
Practice this every day, even every hour until you make progress and can focus better. If you cannot rein the thoughts in, you might try calling your doctor and asking for advice (maybe a therapist can help dig out why you have the issue and then help you steer back in).
The only way to get things done is to just do them – and do one thing at a time (unless you are good at multi-tasking). Repetitive brain training will get you where you need to be. Navigating Deadlines Critiquing Your Presentation Brain Fog Don’t Take on the World Don't Procrastinate Put Your Work Aside for a Day College Admission Prep PR