This is a good question because I battle with this sometimes too.

I had a quick look for blogs because I'm also interested - I lack focus sometimes and I could do with some strategies.

I found this good blog here on PsychCentral. Whilst it is written with ADHD in mind, none the less - I think that there are some strategies that are worth while me noting. I hope that you might be able to find something of personal interest / value to your personal situation too.

Here's the link

15 ADHD-Friendly Tips to Fire Up Your Focus | Psych Central