That having been said poe currency, it is important to stay healthy and sane, and 16+ hour days aren't healthy. After four or five days of living and breathing Path of Exile, my body was crying for rest, and my palms had cramped up.
It's worth mentioning how important sleep is. You make better decisions when you are well-rested. If you don't get enough sleep during the time that you're competing in a Path of Exile race, you may make a sloppy mistake and die.
Throughout long grinding sessions, make sure you step away from the computer every couple hours. Spend 30 minutes doing something which doesn't entail looking at a display. Have a walk, run some errands, or cook a meal.
It's not the end of the world in case you die or do not get a Demi. I died twice at the Turmoil race. The second time was very unsatisfactory because I was at the top five for my course at the moment, and this was the very first race I'd ever attempted to triumph. Both of the times I expired involved older mechanics, but I heard from my errors.
Back in Mayhem, I made a stupid choice on day six and expired buy poe chaos orbs, but made another character instantly and kept pushing. I had been in 2nd spot for my class when this occurred.