Chasing down a championship lead can be both liberating and extremely stressful. On the one hand, your objective is simple: beat the rider who is leading the championship, and try to outscore them by as much as possible. On the other hand, you have to take more risk, as riding conservatively means you risk not scoring enough points to close the gap to the leader. Finding the balance between the two is always difficult.
Defending a championship lead is just stressful. The best way to defend it is to keep trying to win races, and make it as hard as possible for your rivals to catch you. But winning races means taking risks, and a crash can mean throwing away a big chunk of your lead in a single race. Riding conservatively is not necessarily an easier option: it is paradoxically harder to ride just off the pace than right on the pace, requiring more focus and concentration to manage the race. Giving away points every race can be like Chinese water torture, your rivals closing the gap with each drip. Tension rises every race, and containing it without bursting is extremely stressful.
The Motegi MotoGP race provided a perfect example of both of these situations. Valentino Rossi and Jorge Lorenzo came into the Japanese Grand Prix knowing that they had to win the race if they were to retain any hope of keeping the 2016 MotoGP title out of Marc Márquez' hands. The job was significantly easier for Rossi than for Lorenzo. Outscoring an opponent by 52 points in four races is easier than trying to make up a deficit of 66 points. Conversely, that put more pressure on Rossi: keeping an achievable target within reach makes winning paramount.