I have a ~routine, where each successive step assumes the previous step didn't work to overcome the slump. Usually one of these works, but sometimes none of them do!

• Try doing the work while standing up.
• Get up from my desk. Walk downstairs & go to the toilet, or get a drink, or a snack.
• Take a 10 minute break.
• Do something else that needs doing (but seems easier/doable in your current state).
• Listen to music while attempting to do the task.
• Start a pomodoro with someone else.
• Go do some exercise/take a walk.
• If emotional: try resolving the emotions directly.
• Ask for help/advice from a colleague.
• Give up for the day, and try again tomorrow.

I have a couple of strategies and maybe you already employ some of them. Before I list them, I think it is worthwhile to get some objective assessment of your productivity given the perhaps not too infrequent slumps in productivity. I thought I would be much less productive than the average EA being a hopefully ~equal parent with much less time to work and was surprised people thought I was able to do a lot in a short amount of time! So I do not fret so much about productivity - that in and by itself might cause productivity loss.

Here are what I think are my main strategies:

• Energy/motivation management - as much as possible, work on the least motivating but important tasks when you have the most motivation. Make this a priority for how you organize your life. So other things like working out, cleaning, etc. are things you can fit in when your motivation/energy level is low
• Longer list of somewhat relevant but exciting tasks - have some tasks lined up that might not be the top priority in terms of effectiveness, but that is super exciting to you. If you used up all your workout, cleaning etc. time from above, you can then work on these tasks.
• EA Gather if you are not in an office. Seeing other people work and chatting with them in breaks helps!
• Drugs and stimulants, but be careful. Caffeine of course, lots of blue infused lighting, motivating music. I use nicotine as I seem to have stunted dopamine receptors but would be super careful here if you might be more likely to get addicted and would steer away from anything that has potential, large downsides.

If I'm truly stuck on a task - no matter how hard I try, my focus always slides off of it - I set a timer for 10 minutes. During those 10 minutes I give myself free licence to either work on that one task, or just sit in my chair. I often spend a few minutes noticing a variety of feelings. Eventually I often hit a thought like, "Well, I wish I could make progress on this, but I don't really even know what to do. How would I even start?" or "I want to do so much more but I'm just exhausted; I'm at my limit" or "I'm not sure this task is even that useful." That is generally the thought that gets me unstuck.

This won't be the answer you're looking for but honestly, time permitting, I just take a day or three off. I find when I'm relaxing, giving myself space to breathe and think without force, that's when creativity starts to flow again and ideas come in. Obviously this isn't deadline-friendly!