Startup Idea: Productivity Enhancement Software

Startup idea to develop a productivity-enhancement software that allows users to designate a predefined amount of time for leisure activities, such as browsing on the internet, video gaming, and streaming videos, and then restricts further access once the limit is reached.

I am a person who struggles with time management skills. Specifically I have problems with balancing out entertainment and productivity. There are some days when I wake up and all I do is go on my computer and cycle between video games, wasting time on reddit, and spending hours upon hours watching videos on youtube. If there was some sort of service that allowed me to watch only a predefined length of collect video time on youtube I would gladly pay for it. A similar thing should exist for reddit, or just browsing the web in general.

The ideal system allow me to input how much time I am willing to spend on these sites or watch videos for that day and then offer a mechanism for disallowing additional use. I have tried the pomodoro technique in the past but nothing related to software.