The idea of tapa encourages the yogi to not desist from their useful habits due to physical or mental difficulties encountered along the way. One may feel that the discomfort they experience puts them off of the idea of continuing; however, by showing endurance, the yogi can continue to make progress.
There are three different types of tapa. These are known as sattva, tamas and rajas. They each denote a different approach to the idea of endurance through difficult moments or discomfort.