In the internal arts, the internal feeling of a practitioner acts as the ultimate yardstick for power training. Simply put, a feeling of strong sluggishness or resistance is a clear sign of power training in action. In other words, if your movement (for example when doing standard tai chi form) does not encounter an internal sensation of powerful resistance, you are doing proper training in power. Having said that there are other training objectives other than power training and to achieve such "other objectives", different internal sensation will be required. That will go outside the scope of this little training note.
To the beginning student, however, a more operational instruction will be needed to facilitate him to cultivate a stronger sense of resistance. The method is simple: keeping your stretched hands stationery when doing defined (and simple) movement exercise.
The most simple exercise is doing push and pull using combat stance. Keeping your stretched hands fixed resulting (visibly) your body moving forward and backward (while keeping the leg-part of combat stance almost fixed too, i.e. do not transfer your major weight to your front feet at end of pushing). In addition your focused mind should be at the center point of your arms - body forward on triceps and body backward on biceps. After some experience, a student can transfer such learning effect to other movement forms, by himself or with the help of an experienced teacher.
In the advanced movement form like Tortoise Surfacing Water (神龜出水), fixed or immovable hands together with no weight transfer, is of vital importance to proper training.
So much for today!