How do you guys manage to write thousands of words in a day?

I've been on this subreddit for a while now and I always see people here claiming how they've written thousands of a word in a day. How do you guys even do that? Don't you have any hobbies? And what about responsibilities like jobs or school/college? And do you guys not burn out and stuff? Would appreciate some advice on how to balance some of these other things with writing.