Something I've been doing lately is this position, not low in the horse-rider stance like the poseur here, but in a more upright position where arms and legs tire at the same pace. You can start with your feet shoulder-width apart and adjust, hold the arms forward and fingers in one finger zen. Knees bent, gently sinking into a standing-seating position, completely relax. A couple of minutes twice a day.
I swear it feels like it's toning my nervous system.
In Chi-kung this is called The Golden Bridge.