Body is not stiff, mind is stiff.
Yoga is an internal practice. The rest is just a circus.
Yoga is for internal cleansing, not external exercising. Yoga means true self-knowledge.
If we practice the science of yoga, which is useful to the entire human community and which yields happiness both here and hereafter - if we practice it without fail, we will then attain physical, mental, and spiritual happiness, and our minds will flood towards the Self.
Do your practice and all is coming.
So whether you do your first downward dog at 14 or 44, it’s not your history but your presence on your mat that counts.