What a great way to live life. To know what brings you joy and do it every day!
Periodically, I question myself and ask "What makes me want to get up in the morning excited to start the day?" If I can wake up every (or most) mornings and look forward to the day ahead, then I know that I'm following my dharma and living my passion.
In The Heart of Yoga, TKV Desikachar defines dharma as duty or ethical value. In Light on the Yoga Sutras of Patanjali, by BKS Iyengar, he describes dharma is the 'first of the four aims of life, science of duty, religious duty, virtue.' Sometimes Iyengar simply equates dharma to duty.
My favorite teacher on the subject of dharma is Aadil Palkhivala, founder of Purna Yoga. He has a brief YouTube regarding the subject. He talks about the importance of knowing yourself in order to know who to "be". Otherwise, we tend to attempt "being" someone that we are not.
"Dharma is the reason you are alive." - Aadil Palkhivala
Yoga is a tool to help you find and live your dharma.