I use an app called aTimeLogger on Android that just pins a little notification with a play/pause and stop button, and a little time counter. When I start working, I hit play. When I take a break, I hit pause.

Been doing this for years. It's great to help me focus on working when I'm actually working, and doing other stuff when I'm not actually working.

Looks like the app is available on iOS too if you're an iPhone user.