Keeping going
Attention residue
Part of your mind stays on the last task when you switch — especially an unfinished one.
Switching away from a task you didn't finish leaves "residue": part of your attention stays on it, and you perform worse on the next thing.
A later study found a simple fix. Before switching, people wrote a quick note on where they stopped and what came next. That reduced the residue.
Try this
Before your promise, write one line about where you left whatever you were doing.
Sources
People switching away from an unfinished task carried attention residue and performed worse on the next task.
Leroy, S. (2009). Why is it so hard to do my work? The challenge of attention residue when switching between work tasks. Organizational Behavior and Human Decision Processes, 109(2), 168–181.
A brief "ready-to-resume" plan reduced attention residue and improved performance on the interrupting task.
Leroy, S., & Glomb, T. M. (2018). Tasks interrupted: How anticipating time pressure on resumption of an interrupted task causes attention residue and low performance on interrupting tasks and how a "ready-to-resume" plan mitigates the effects. Organization Science, 29(3), 380–397.
A general finding about how people tend to work — not advice for your situation, and not a diagnosis.