Maybe I´m not the only one thinking about food when hearing the word “tapas”?! And indeed, it is the same word. In Sanskrit this word literally means “heat”. And in English the most common way to describe it is “self-discipline”, but one could also translate it as spiritual effort, change, or transformation, which might be more “enjoyable” or at least appealing for me. Transformation has for me more of a positive meaning. But as so often with both the yamas and the niyamas, this is no walk in the park, so to say.
Tapas has the sense of “cooking” ourselves in the fire of discipline to transform ourselves into something else.
Tapas is the day to day choice to burn non-supportive habits of the body and mind, choosing to forsake momentary pleasures for future rewards.