You often hear in a yoga practice to do these three things:

Ground down through your big toe mounds

Lift up the arches of the feet/tone the belly

Broaden the chest.

It would be interesting to investigate in your own practice how easily you are able to do these three things, each on its own, and all three simultaneously.  A balanced Yoga practice would involve, among other things, a fine-tuned awareness of these three subtle movements, and the practitioner should aim to move in these three directions with equal amount of effort - simultaneously.

I would argue that these three movements represent energetic pathways that can get blocked by certain kinds of thoughts/mind states.  The big toe mound grounding represents one's ability to stay grounded, to quiet down the chatter of the mind, to feel stable in poses (and life), and if you are, like me, too much in your head, always with your thoughts, indulging the inner chatter too much, you would often neglect that important grounding action.  Fear, anxiety, and insomnia are common mind states when grounding is lacking.

The lifting of the arch of the toot, pulling up the inseam of the legs into the lower belly, where hip points move towards each other represents our ability to tap into our sense of self, to have a good, healthy self with power, yet in total control of that power.  Not threatened by others, this Self does not feel the need to diminish others to feel important.  This open, accepting, uncritical, yet confident mind state taps into our core power.  This action suffers when we are too critical of ourselves or others.  With arches of the feet being too high or too flat, we may be nursing latent (or not so latent) anger, frustration, and be blinded sometimes to the truth before our eyes.  Our ability to let go of events and to move on may be hindered.  Taken to the other extreme, tight, ultra-toned (and exposed to show off) abs may speak of an overdevoped ego.

Broadening of the chest is a necessity in Yoga practice, where spaciousness and ease around the heart are cultivated and treasured.  A spacious, yet soft heart center is filled with joy when it is balanced, it is able to give and receive love.  The heart can close in two ways - it can collapse onto itself, or it can become too pushed forward, hardened against the pain of life.  It can also become emotionally unstable.  So, for some of us the broadening needs to happen in the front body, especially if you feel sadness, grief, emotional withdrawal.  Broadening and breathing into the space of the heart can relieve the deeply held emotions.  If the heart has hardened, especially in the back body, the thoracic spine can flatten, pushing the chest forward and telling others to keep their distance, we need to broaden the back heart.  Sometimes this hardening happens as a defense mechanism.  But sometimes it happens as a result of not so much emotional trauma but due to a constant effort to extend the spinal column (dancers, skaters, etc.), and sometimes it happens due to a long-term Yoga practice that has been too focused on backbends and "heart openers."  At some point the person went too far and did not notice it.  This has its own energetic effect and allows the person to feel protected from judging glares of others, yet sometimes they can be perceived as distant, unfeeling, or the opposite, too forward with their emotions, unstable and raw.

Our ability to be aware of these energy channels and to keep them clear by constantly patrolling them is part of the mental work we need to do to achieve balance in our body and our minds.  Next time you practice, evaluate your ability to execute each one of these efforts well but without overdoing it.  In each pose you do, attend to these three, and see what happens.  Also notice if one or two of these are easier for you to remember and to articulate than others.  Is there one that is especially difficult - you always forget, or it doesn't happen when you think of it, or you feel frustrated or confused by the whole concept.  And then ask yourself if you have felt grounded, self-assured, and open in the heart lately - are you balanced?