Meditation makes the body light and agile

Question: Why do I feel my body becoming light and floating when I recite the Kṣitigarbha Sūtra?
Answer: This is a state that arises from meditative concentration. When the mind becomes tranquil, the flow of qi and blood encounters no obstruction and circulates smoothly, causing the body to become soft and light, as if boneless. Practicing while young is advantageous, as the body's constitution is robust; with just a little mental stillness, the qi and blood become lively, and meditative concentration emerges. Additionally, an individual whose mind and thoughts are simple and unpolluted by much defilement finds it easier to attain mental stillness and meditative concentration. Furthermore, possessing the heart and conduct of a Bodhisattva—having the aspiration and undertaking, being joyful in helping others and practicing the Bodhisattva path—greatly enhances the effect of one's own accumulated merit and the blessings of Buddhas and Bodhisattvas. Those with aspiration and undertaking, upon achieving realization, will benefit countless sentient beings; hence, the blessings of Buddhas and Bodhisattvas supporting them are immensely powerful, accelerating their own practice.
Those who have practiced for many years without progress should regularly examine what conditions they lack in various aspects and strive to remedy them as much as possible. If the reason is the absence of bodhicitta, one should frequently contemplate the suffering of sentient beings, reflect deeply on the kindness of all Buddhas and Bodhisattvas as well as the kindness of sentient beings, nurture a heart full of gratitude and the wish to repay kindness, broaden the mind, extend compassion from oneself to others—then generating bodhicitta will not seem so difficult.
When meditative concentration arises, one experiences a separation of mind and matter, perceiving the insubstantiality of matter, thereby discovering the truth and realizing the ultimate reality. When mind and matter are not distinguished, the mind becomes obscured by matter and cannot perceive the true nature of matter; ignorance remains unremoved. Discovering the insubstantiality and unreality of matter is relatively easier; discovering the insubstantiality and unreality of the mind is extremely difficult. To realize the ultimate truth, without meditative concentration, there is nothing to discuss.
Although one may rise from seated meditation, the mind continues to sustain the state of concentration experienced during meditation. This demonstrates that the meditative concentration attained through seated practice nourishes the active concentration during walking, standing, sitting, and lying down, enabling the mind to abide peacefully in concentration at all times without distraction. Someone once claimed that seated meditation is useless, arguing that since most of a person's time is spent in activity, and seated meditation occupies only a short while, concentration vanishes as soon as one becomes active. Facts prove how misguided and unfounded this person's statement is. Having never practiced seated meditation themselves, they oppose everyone's cultivation of concentration, understanding nothing about practice.