Seriously, I'm not joking here. If you live in a state that allows you to, then smoke some weed.

not what you want to hear but if it is that noticeable to your function I would see a doc and at least get some bloodwork done

If you have a sedentary lifestyle, start walking. I am more focused these days since I have had to walk 3 miles a day.

What you are trying to focus on makes a huge for me.

If I am having fun, I am like a freaking laser.

If I am doing documentation at work that I know, no one else is going to read, my mind wanders just a tad.

And by tad, I mean... wait, what was I saying?

I've noticed in the last few years that leaving myself notes helps. I write them as I think of things and leave them where I can find them in advance. I leaver some on my car passenger seat often. Examples are going to the store, getting gasoline, bank visit, etc. Try this, get plenty of rest, and talk freely with a doctor about your problem.

Stay away from anything containing cafeine. I had trouble focusing and took ritalin - enabled me to have career. Talk to doctor. Ritalin is bad for the heart.

Mindful mediation can be useful.

Mindfulness meditation. Try the headspace app. Or MHK

Brain games. I'm finding myself pretty insanely forgetful lately, so I'm playing brain games and doing focusing tasks.

Have you consulted a physician?
That might be a good place to start.

More sleep. I need 9 hours. Unusual for a 52 year old but, it is what it is.