Isn't it so?
The most difficult part of the Light Body Technique is its prerequisites.
For instance, the Lightweight Step requires understanding the true meaning of the wind, thus learning to observe the wind and recognize the opportunity, which means one must jump off a cliff.
The Confusing Wind and Cloud Step is most challenging in terms of the physical and true qi requirements.
If a normal person were to practice, just these two prerequisites would deter countless people.
But for Xu Lingjun...
Physically resilient?
How resilient? Does taking a bullet in the face count?
As for explosive power, just considering Xu Lingjun can practice 'Qiantian Gang Qi' as routinely as eating meals, three times a day, and he can even reverse his own true qi and explode it...
Who dares say he lacks explosive power?
Even Sister Yaya and Teacher Su wouldn't dare say that together.