Install BlockSite extension for your browser (say no to the adult site blocking thing, no need to track your visited pages). Use a custom blocklist. Mine for start:
gmail.com - don't check mails (also make sure phone is far away)
google.com - don't search for random stuff (will surprise how many random stuff you would search)
mailchimp.com - don't check subscribers
indiehackers.com - :|
Schedule some time when you unblock the extension and sort stuff out. For example before lunch - this is better than after, since hunger will chase you away quickly.
Also subscribe to get special content for https://treetide.com/book/programming-without-anxiety ;)
Ok, now back to blocking & off for lunch.