Heart is the place of emotion, ego, and attachment. You have to rise above all the propensities of the heart. Clean it thoroughly, surrendering it to God through regular prayer and meditation, and through sincere and steadfast effort.
Any holy book that gives you spiritual motivation is good, but one should not develop ego or pride with one's knowledge of the scriptures. Theoretical knowledge is not enough in daily life. Practical experience is essential.
Passion, anger, greed, vanity, self-arrogance, pride, suspicion, and ego also give some inspiration and evolution.