There are two ways to build a strong body construction…

The first one is building up by shrinking and tensing up. This construction is rigid. It could be firm like stone, but it also can be brittle, like a mud house.

The second one is building up by expanding. Then, our bodies are supple, elastic and light like a bouncing castle.

It is valid not just for the body but also for the mind.

“Men are born soft and supple; dead, they are stiff and hard.
Plants are born tender and pliant; dead, they are brittle and dry.
Thus, whoever is stiff and inflexible is a disciple of death.
Whoever is soft and yielding is a disciple of life.
The hard and stiff will be broken.
The soft and supple will  prevail.” 

Lao Tzu