Don't allow yourself to do anything non-work on work computers. Don't allow yourself to login to any reddit/HN/other sites from any computer. Disable networking

Don't allow yourself to do anything non-work on work computers. Don't allow yourself to login to any reddit/HN/other sites from any computer. Disable networking on your computer when you need to use it for productivity. Basically put awkward barriers between you and the internet so you don't have an easy means to slip-up.