When you practice the Tai Chi form and are deeply relaxed and focused you can lose your sense of time. 35 minutes of practice feels like only five minutes has gone by. This doesn't necessarily happen as a beginner student but with regular practice you will feel really good every time you practice Tai Chi. This article is a good discussion of the "flow" state. https://www.sciencealert.com/the-science-of-why-flow-states-feel-so-good-according-to-a-cognitive-scientist?