"Tapas" in Yoga are one of the Niyamas and often translate as "discipline" or "austerity". It can be viewed in the spirit of inquiry or exploration. This exploration on a deeper level helps us find our true selves.
Tapas are the willingness to work hard and deepen our practice, to further our journey with honesty. These virtues are the basis on our desire for spiritual well-being. This desire will offer us consistency. We will have good days and bad days, days when the spirit is willing but the flesh is weak, and days when the opposite is the case. Years of consistent practice are not built on rigid self-discipline; they are built on the desire to know more.
Be curious in life....on your mat....and in your thoughts.
Tapas can be described as "burning enthusiasm". You don't have to be so serious and solemn. Just heighten your desire for personal growth which will always remind you of how much you love your yoga practice!