Preparation for World Championship matches

I've been reading Tibor Karolyi's "Mikhail Tal's Best Games 2: The World Champion," and thinking about how elite level players prepare for world championship matches.

Does anyone have any knowledge about exactly how various players prepare for these matches? Beyond playing a lot of practice matches, what goes into their preparation? What does a "second" do? I doubt that an elite level player would have any trouble memorizing various "lines" and sub-lines, so what is the role of the various seconds and assistants and trainers?

Well, Botvinnik beat Tal in a rematch. If I were a second back then, I probably would have looked into this N1e2 move blocking the bishop. Was it common back then? I see current databases with it as an acceptable move, the computer has no problem with it, but back in 1960 was there established theory that said this was a good move? It is ingenious to my eyes. It frees up the LSB after Nf4 attacking black's LSB instead of white's own LSB, and then it can go to b3. From there white can apply pressure on the kingside without losing the queenside pawns. 

My guess is that a second for Botvinnik would look at that and look for ways to prevent this from happening.

Yes of course. 

What other things would a second do? How many seconds would a player have while preparing for a championship match? Would each one have a different role?

What are the physical things a player might do in preparation? Exercise? Diet? Sleep regimen? 

What I'm curious about is specific details of how various elite players prepare.  I know how boxers and basketball players prepare for important contests. What about elite chess players? 

The role of a second has changed enormously since the days of Tal and Spassky. These days the second--or team of seconds--spends an enormous amount of time on the computer, researching the opponent's games, and studying specific opening lines, sometimes almost up to move 30! And if the opponent comes up with unexpected lines during the match, the seconds sometimes work all night coming up with new lines. On the other hand, the modern second doesn't play an important role helping his player analyze adjourned games, since there are no adjourned games

I don't have Netflix. Isn't that a subscription service? I just don't have the money to subscribe to any service other than my regular TV and internet service.  I don't even have HBO. Oh well.

Very interesting! Does anyone else have any other insights into match preparation? Even the way elite players of the past prepared...

There's a book called "The Anand Files" where members of "Team Anand" discuss the work they did to prepare Anand to win three world championship matches in a row. It goes into enormous detail about their preparation work

Thank you! I will look for that book.

@Almita7 what is so special about that movie? why don't you tell me what important things regarding chess in that movie?