If you're distracted by internet related stuff; websites, etc. You can configure your firewall/proxy to white list mode and add only the IPs/domains that are for work.

If you're distracted by non-internet related stuff; software, games.. You can set up a virtual machine and stay inside that with all your work related files, or set up your main drive for dual boot and have a separate partition with an OS with only your work files. Dual boot method would be more strict cause you'd have to reboot your computer to get back into your main OS. I used to do this a lot, get work done in the work OS and when its time to game/break I rebooted into my main OS.

In reality you don't have to do any of this. Instead, training yourself to have more self control will help you from becoming distracted in all aspects of life. It's all mental, find something interesting about your work and study it, get involved in/create side projects that are relevant and beneficial to your main job. Learn, create, expand. Distract yourself with "good distractions".

Eventually you might lose all interest in the field you're in, you've mastered/studied everything in it, at this point I would recommend teaching others or writing books, passing on your knowledge for the future.