Most people think of warmups as something physical, but a short mental warmup can be useful too. Before a study session, a gaming session, or a block of focused work, a few quick challenges can help you notice how sharp or distracted you feel.

The important thing is to keep the routine short. If the warmup becomes a project, it stops being useful. A practical routine can include one reaction challenge, one memory challenge, and one attention-based task. That gives you a quick sense of speed, recall, and focus without taking over your day.

For this kind of routine, a browser collection of online brain tests works well because the tests are easy to start and easy to repeat.…