You might have heard about Yoga as a form of gentle exercise.
That is correct, but there is more to it.
Yoga is a system of values and conduct. The same you and I learned at school. Don't harm others, don't accumulate excessive wealth, and be truthful to yourself and others, and you can always explore when you are ready.
From this philosophy of life, Yogi scholars have created techniques which help us with our self-development. You have physical exercises for a "solid" (strong) and "light" (supple) body, breathing methods for expanding vitality, and techniques that help you focus on your affairs.
In a time we are pushing speeds to the maximum, Yoga teaches us that we also need to slow down and make sure we are aware of what we do automatically, like our posture, the way we breathe, interact with the world, our mental processes and emotional responses. If we are not aware and re-learn these, we can stress our body and mind and bring discomfort, if not a disease.
We praise science today, but all have been discussed and identified correctly thousands of years ago. Modern science now has the tools and proves Yoga and its techniques are correct and help us keep fresh and face ageing with grace.