The Tai Chi classics talk about full and empty, but how can you put this into practise?
You can do this in your form.
As an example, when turning to the right from Ward off left in the Cheng Man Ching form, completely empty your right side. It's as if it was full of water which has drained into the left side of the body.
This includes the legs. The right side then feels incredibly light. When I turn I visualise an attack coming to my right side. I have to sink, empty and make space.
A common mistake is to turn but not empty, so your energy is stuck and double weighted. Visualisation plays an important part so it essential to have an understanding of the martial applications.