I once read about how Master Yu Yongnian of Yiquan fame was taught to stand in zhanzhuang and mentally practiced pulling a distant tree and pushing it back. Master Yu related how he practiced this for 3 years before understanding the teaching.
I told my student that this sounds funny to those who are not tuned into the internal arts methodology. However, if he can understand the implication of the Tai Chi principle on page 129, TaijiKinesis Vol 2 he not only can understand this pull-push tree practice but can demonstrate the power that can be acquired.
To underline my point I applied it on him. This was after I had explained and shown him different ways the intention can be used to generate power with different effects. Thinking back I think I like the dragon spitting ball power principle from Grandmaster Wei’s form the most because the effect is interesting.