Certain experiences make us mindful naturally. Say, you are learning a dance. You will be so immersed in the dance, that you will not be able to think about anything else. You may have had many bothering thoughts up to that moment, but when you are learning the dance, you are completely present, in the moment, not judgmental and not bothered by your thoughts. That is mindfulness.
Even though the process of learning the dance (or song, or anything for that matter) itself may be challenging, after the experience, you feel relaxed, rejuvenated, and happy. This is the magic of a mindful experience.