We're all programmed a little differently! My partner (he happily admits) cannot multi-task. Changing up something freaks him out, as he has to focus on one thing and then move to the next. I'm the complete opposite, where I can switch things up fairly easily. I have had year's of experience managing events, schedules and campaigns, and things almost certainly never go to plan, which just forces you to lean how to multi-task.
I actually try not to! I do one task after the other. Context switching is a productivity killer, so when needed (for certain tasks) I turn my phone off, and close/block unrelated tabs. It's a mix of self-management and using the right tool, but it works. I prioritise my tasks at the start of the day, I use the calendar blocking technique for that. Hope that helps!