As this is the Swyama Siddha Hanuman Mantra it doesn't have to be chanted for a hard and fast number of Mantra Repetitions for being able to utilize it. Exclusive worship and rituals and regulations about way, sitting down mat, and counting rosary are usually not advised for chanting this https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s