To achieve Enlightenment, we need devotion and confidence in Buddhahood. Without these, it is difficult to attain to a spiritual quality in the mind. Just as a rotten seed cannot produce a healthy plant, so faltering devotion cannot produce virtue. Devotion and confidence mean an understanding of cause and effect. A positive cause creates peace and happiness, and a negative cause leads to suffering. Afflicting emotions cause different levels of suffering to arise, whereas Enlightenment is sacred and precious, free from confusion and pain. To achieve this state, one must have devotion and confidence in the Buddha as the teacher who shows the path, the Dharma as the path itself, and in the Sangha as the community which cultivates the Enlightenment mind and acts as a guide to Buddhahood. Devotion and confidence are like water to a seedling; if one is endowed with these qualities, one can meet many great masters and receive the precious teachings. So when the precious human body containing the Eight Freedoms and Ten Endowments and in addition possesses devotion and confidence, the being has the basis for achieving Enlightenment.
It is asked why, if we are born as humans many times before, and have met spiritual masters, we did not previously achieve Enlightenment. The reason is that we fell into conditions of error such as attachment to this life, attachment to samsaric pleasures and laziness, attachment to our own liberation, and not understanding the method for achieving Buddhahood. To dispel such errors, there are four antidotes: the contemplation of impermanence, understanding the suffering in samsara and the truth of karma and result, the practice of loving kindness and compassion, and the cultivation of the Enlightenment mind.
Obtaining a life of leisure and endowments is like arriving at a continent of jewels.
Whether we attain liberation or not is up to us.
Be sure, therefore, not to leave empty-handed.
This is my heart's advice.
(from Jewel Treasury of Advice)
http://www.purifymind.com/PreciousLife.htm