What are the indicators of a clean heart and mind?
What constitutes impurities of mind in the spiritual area? All those unwanted byproducts of the endless string of worldly attachment that exists within your mind. If your mind is deeply attached in the world, then you can be sure that it is also feculent. The barometer to gauge the depth of your worldly attachment is to see how bad you feel when you lose someone or something that you loved. Inversely, how good do you feel when you get something or someone that you love? If these feelings of good and bad reduce with your devotional practice, then it means that you have made some progress towards cleansing your mind.
The most effective way to evaluate the true state of your mind is to see how deep your attachment is to God and Guru, and everything associated with them. What is the extent of your eagerness and desperation to know about God and to meet God? This is a far more reliable means of self-evaluation than the one described initially, because even in the world an illterate, uneducated person can appear to be completely detached from the world.
How can we practice non-stop devotion while living in the world and performing all our worldly duties?
This agitation in your mind and feeling of discomfort due to the loss of precious time for spiritual practice is a form of sadhana in itself; it is a kind of devotion. However, similar feelings in relation to the loss of precious office working hours are only valuable if you devote every moment of your remaining time to devotional practice.
Original answers given in Hindi by Jagadguru Shri Kripalu Ji Maharaj