Vaishnava Samhita. Premanidhi Charitam. Vol III Book VI Chp 19 Shlokas 13 - 14

युक्तं नियममास्थाय दृढनिष्ठो यथारुचि |
कृष्णमाराधयेन्नित्यं सा परा भक्तिरुत्तमा ||
प्राणांस्त्यक्त्वापि नियमं पालयेत् सुदृढव्रतः |
प्रीतो भवति गोविन्दो भक्तस्य दृढनिष्ठया ||

Each one should firmly engage in some routine sevice to Shri Krishna suited to one's taste and capacity. This is the characteristic feature of true devotion. A staunch devotee should not give up his routine even at the cost of his life. Shri Govinda gets gratified only to find such sincere involvements on the part of His devotees.