Firstly, I'm not asking how to practice to get better in CP. There are tons of posts for that. I'm curious to know how most of the top CPers maintain their mental stamina to practice longer?

Like, during practice...

Do you sit for like 3 or 4 hours in 1 go? and then take a long break for 1 hour or a 2 and come back? Or do you solve a problem above your skill level, say it takes around 1 hour, and then take a 20 min brake? In that case what do you do in the break? Sleep? Eat? Pushups?

Or do you follow some other break strategy? In short, what works the best for you to maintain your mental stamina?

I would love to hear comments on this from high rated coders.

(A lot of opinions are there that one should focus on what your learnt on a day and if one has, then its productive day, but for those who are considering to participate in top contests, especially beginners, time is a very important factor to organize their training plans. So maintaining a high mental stamina throughout becomes a high priority.)