Ideally you're always so excited about tackling your next task that the only motivation you need is another cup of coffee. Unfortunately we don't all live in that world. If all you need to motivate yourself is a simple reminder that the clock is ticking, Maker Eugene Baumstein's web-based 24-hour countdown clock does what it sounds like.
If timers help but you're looking for something you can actually set custom timers, alerts and breaks with, take a gander at the free, cross-platform timer app Focus Booster.
You've got 24 hours to get shit done [Eugene Baumstein]