Fasting for a day in the name of the "Lord" is tapas. Facing insults and honour equally is tapas. Suffering heat and cold with perfect mental equanimity is tapas. To serve is tapas. To "love" is tapas. To "pray" is tapas. Any "action" consciously done towards one’s own deliverance from the present limitations as a samsarin is tapas.
Be a tapasvin and learn to tap the very source of all "life" and "joy" that is within "thyself."