Simple "task timer" dings every 15 minutes
I'm sure there are lots of smart phone apps that do this, but I have a "dumb phone" so I was happy to discover this nice, FREE, desktop computer app.
It's called "Task Timer by Clinton Begin" and has a very simple interface where it dings on the :00, :15, :30, and :45 minute mark of the hour.
Instead of setting a timer and starting, it just marks the clock for you. So, it doesn't work so great for doing a series of 15 minute bursts with breaks in between, but it's helpful for when you're doing a longer task. Then I have a task for "tea break" and I do that for 15 minutes or so.
It helps to remember that time keeps going when I take a break, and it forces me to pull focus and pay attention every 15 minutes, to figure out whether I've lost focused or if I'm still moving forward on a task.
You list your tasks that you want to accomplish, and and there's a row of bubbles after each task (like those old scantron tests), 4 bubbles for each hour of the period you say you want to work (up to 15 hours if you want to track all day). You fill a bubble for whatever task you've been working on.
It's nice. And free. I like it.