Six meetings, no gaps, and the kitchen is on the other side of the building. By meeting four you're running on nothing and there's no window to fix it.
Back-to-back calendars are one of the more common complaints about office and remote work — there's rarely five free minutes, let alone enough time to make or buy a coffee between calls.
A few things help: blocking 5–10 minutes between meetings where you can (even if it means pushing back on the calendar), keeping water at your desk since dehydration alone can feel a lot like tiredness, and having something you can have at your desk between calls without leaving the room.
That's the gap Neuchu fills for a lot of people stuck in back-to-back calendars — 50mg of caffeine, no kettle, no queue. You can find it here.