A strong foundation is what keeps any building standing without collapsing. No matter how good a building looks, if the foundation is not strong enough, it will not be safe to live in and will not be comfortable to live in.
Yoga has a concept of the chakras, and the first priority is to activate the root chakra, which is the lowest chakra on the end of the spine. It is the life force, the root of life and the vitality. By placing your feet firmly on the ground and standing strongly, you activate the root chakra and it brings you full of power. In my yoga classes, I never skip this standing posture, the mountain pose. I never skip to give instructions of the mountaion pose from the feet to the head every class, not only to let the students stand strongly, but also let the students be aware of their own whole body. Some students may be fed up hearing the same instruction, but if you neglect grounding, mountain pose and full-body awareness, you will not improve the other postures.
Many people today does not seem to be grounded firmly. They pay attention only on their heads and minds, and they look unstable in physical and mental, as if they could fly away if the wind blows strongly.
As you get old, the first thing to weaken is your legs and feet, and when these weaken, everything on you weaken.
Stand storongly, firmly and conciously!