Startup Idea: Focus-enhancing anti-distraction app

Startup idea to develop a smart application to promote productivity. The app should recognize when the user is getting off task, and then subtly remind them to refocus on their work instead of forcefully restricting access to distractions.

As a person whole works in a job that requires deep concentration, distractions are a constant threat to productivity. There are productivity timers to encourage you to stay on task for a fixed amount of time, but these require a self-discipline that takes time to develop, and so it's hard for the chronically distracted to get started with them. On the other hand, there are, e.g., website blockers that are perhaps too hard a constraint on one's computer usage. A useful middle ground might be an app that "notices" when you're getting off task, but only gently reminds you to go back to your work instead of firmly blocking the behavior.