Zheng Siwei tends to take it a bit too serious, I believe as he matures he would learn to deal with the burden of the pressure of expectations better.
I think it's because he was expected to play MD rather than XD and he chose to focus more on XD,so he wants to prove that he makes the good decision
I won't be surprised if it's the two teenagers themselves who are eager to grow up quickly and attain huge success as early as possible.
By all means try to take the shot early but don't always have to hit hard, watch where the opponent is standing or likely to do before executing your shot.
Zheng Siwei is so speedy that I think he sometimes got to pause a fraction before playing his shots, to time it just right, not too fast nor too slow.
I'm just worried about their fitness.At the age of 20 they are still building up their muscles and developping their power. If they play too many tournaments it's going to be bad for their future and they will be easy to get injured around 25. LXR is such an example. Rising up at 20,winning an OG gold at 21,played tons of tournaments in during the next 2 years,suffering from injuries between 23 and 24,and a broken knee at 25...