Choose one task small enough to make visible progress, then set a focus interval you can actually sustain. The traditional 25 minutes is a starting point, not a requirement; shorter intervals are fine when energy or attention is limited.
During the interval, note distractions instead of following them. When it ends, take a real break and decide whether to continue, switch tasks, or stop. The Pomodoro timer should help you begin and rest, not measure your worth by the number of completed cycles.
If a task repeatedly overflows, split it into a first action you can finish or evaluate.