Consider a seed patient in the earth. Rain triggers growth. The seed's first act is to send a root down, gathering nutrients, so a shoot can thrust up. Gravity doesn't do the work. Gravity simply allows the seed to tell up from down. 

In the human body it is the same. Dantien/mingmen is the seed. Our root actively drives down from here so our spirit can thrust up. Gravity won't do the work for you. It assists but you still have to actively drive down through the legs and into the ground. Only then can a free spirit reach up the spine for the stars.