A lot of people answering this struggle to understand what highly-specific means. I'm looking to, for the sake of experiment, highly-specific advice that gives a reader clear understanding of what they should do. Unlike the vague advice, on the contrary, that may be too abstract to get implementing it right away.

Inspired by this post but I wanted to change the question a bit to avoid the really vague answers as well as lower the age bar of target audience for the advice.

I'll start with a bunch myself, to give a better example of what I'm talking about:

1. Read The Art of War by Sun Tzu. Ironically, because this is a post about specific advice, dude wrote a book with vague rules on how to do war, but the way it is worded is ridiculously good. If you take your time to think about the advice, you can find their appliances in the most unexpected fields.

I, for example, have improved my skill in videogames, out of all places, after reading the book. Sun Tzu said "If it is not advantageous, do not move". Instead of rushing into combat, I now consider whether my position, current health, location of health packs etc. work to my advantage. Sun Tzu made me realise team-based PvP shooters give you room to avoid and disengage combat, you can make more impact for the team if you choose your battle and have everything work for your advantage.

2. Exercises are not just about a lot of dedication, long commutes to the gym, expensive memberships and the fear of being judged by other gym members. 7 minute workout is a thing and it will give you all the benefits at your own home without the need for equipment, and it won't take much time either.

3. Buy an old used Kindle. For dirt cheap, you will get a device with a good e-ink screen that works without Internet connection, still has decent battery, is light and small. A new thing that makes reading so comfortable will trick you into reading more and books still happen a good medium for sharing information.