Is it possible to get a flexible body being a 40-year-old with a less trained body?

The acquisition of a flexible body is not necessarily dependent on age. Although children are usually more supple and more easily amenable to muscular elasticity, no clear indication exists that inflexibility is explicable in terms of age. I work with kids in gymnastics and fitness who are not my match in flexibility. At my level of understanding of flexibility, age is almost completely inconsequential. Either one is flexible or one is not.

Flexibility is contingent upon 2 variables: Muscle Elasticity; Repetition.

I will treat this question from the vantage-point of a trained dancer. The world of dance – and of classical ballet in particular, uses movement in a specifically stylized mode – diverging markedly from how pedestrians interact with movement.

I have spent a long enough time with the general public as a trainer and so I can shed light on vital misconceptions about physical fitness, with particular emphasis on flexibility. At the outset, I should explain a few important details that differentiate dancers from the general public and show why stylized movement is exceedingly more efficient within the wide scope of human movement.

Most untrained exercisers execute items of movement without understanding why. In dance, the end does not justify the means. Dance is an art form; for that reason, a simple stretch is predicated upon the canonical principles of the art. Let me explain that:

A canon is simply a principle, a methodology. Because I am classically trained, it is clear to me that the best way to achieve goals is to understand guiding principles. You have the freedom to do whatever you want however you choose. But you may be going around in circles unless you understand the method. Learn the attendant technique and you can fly!