I find that the “two minute rule” works pretty well.

Whatever you want to do, set a timer for two minutes. Hit start and do that thing for two minutes and really beleive that after two minutes you can stop.

Once you get going you rarely stop after two minutes. But telling your brain only twos minutes, and let’s see what happens, kind of let’s your brain give you two minutes to focus.

Oh, and go write without a computer. Get a pen and paper and leave ur phone on your desk - go somewhere else. You get to sit there and either write or do nothing. That tends to help too.