Getting into the flow of working takes a while and can be easily disrupted. When you’re in the flow everything seems to work better. Sure, you could hire someone to slap you (brilliant), but one of the quickest ways people get out of the flow is because they didn’t prepare effectively.
Build yourself a ‘flow prep checklist’ and make sure before you start trying to get in the flow you have everything you need from the list (bathroom done, coffee, music.)
What would you put on the list?