When done with concentration, Taiji can focus on many things: the body, mind, forces, and more. There is a connection and overlapping flow of information, such as muscle control through alignment and familiarity, which works with the forces that move lymph and can make you feel invigorated.
To begin, it’s best to work with one aspect, primarily focusing on the internal. Many great practitioners, masters, teachers, and Taiji players have reported spending numerous hours exploring the Taiji map. While the map may be marked, personal experience is necessary for true understanding.
Concentrating on the body leads to the ability to send the mind to different parts of the body, and from there, you can extend your focus out into the distance.
Pay attention to the position and weight of the body, the working muscles, and the fluid alignment of the body. There are many things happening simultaneously. Concentrate your focus on one thing at a time, as multitasking may lead to unpredictable outcomes.