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Maybe some kind of physical activity?
In fact, this is a fallback option to deal with any kind of mental stress, as well as the answer to the boredom caused by desk jobs. But I wouldn't discard reading altogether. It is an all-encompassing thing, and you just need to find what actually interests you, deep down inside, and then read into it to the hilt. In this fashion, you won't be so much relaxed as motivated (more of a roller coaster type of experience) because you will get something else from this activity other than just instant gratification and entertainment (read, it will be more rewarding in the long run). That's what hobbies are for unless your job is that hobby, but then you wouldn't ask obviously (this is an ideal situation but rarely the case in real life, though)
I like that you are still insisting on reading as a way of relaxation. Indeed, it depends on
what you are reading. Manuals for freezers and air conditioners can bore you to death, while something like
Sapiens or
Homo Deus by Harari can literally fill you with life. (It's subjective, of course, but those books have blown my mind recently). And yeah, physical activity. In fact, I combine the three, reading, workout and gambling, when I feel like I need to relax.
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The answer for this is so obvious, if you have a job that drains you mentally, like reading and writing that you have mentioned, you should go for activities that will help you relax your brain cells,
like eating chocolates and sweets while watching TV with your love ones will help you to make your brain recover from stress because of your work, and if you have work that takes too much energy like being on the field, then massage, cold drinks, and hot baths would do the trick.
That's a great advice as well. Spending some time with your loved ones is a great relaxation indeed.

Apart from watching movies and other things, we play online poker together with my SO. It's fun.