When I go to Buddhist workshops most people say their reason for taking up Buddhism is to find happiness, peace, and/or fulfilment. This motivation is good because it brings them to the spiritual path, but it will take them only so far up the path before this desire becomes a road block. I'm not sure why, but in North America, Buddhism tends to avoid focusing on the difficulties associated with the path. I have found that Christian monastic sources can be helpful here because they focus strongly on the suffering and difficulties associated with the path. Perhaps they emphasize this part too much and are therefore not very popular. At any rate here is what Thomas Merton had to say about it. Note that his answer to this question is 100% consistent with the Buddhist answer.
"- the desire which we cherish, in the secrecy of our soul, as our "heaven" sometimes turns, when offered as a solution to common problems, into everybody's hell."
"- it would be singularly unfeeling as well as dishonest for me to suggest that peace, joy, and happiness are easily found along that most arid stretch of man's spiritual pilgrimage: the life of contemplation."
"- One of the strange laws of contemplative life is that in it you do not sit down and solve problems: you bear with them until they somehow solve themselves. Or until life itself solves them for you. Usually the solution consists in a discovery that they only existed insofar as they were inseparably connected with your own illusory exterior self. And consequently another law of the contemplative life is that if you enter it with the set purpose of seeking contemplation , or worse still, happiness, you will find neither. For neither can be found unless it is first in some sense renounced. And again, this means renouncing the illusory self that seeks to be "happy" and to find "fulfilment" (whatever that may mean) in contemplation. For the contemplative and spiritual self, the dormant, mysterious, and hidden self that is always effaced by the activity of our exterior self does not seek fulfillment. It is content to be, and in its being it is fulfilled, because its being is rooted in God."
from chapter 1 in this book