"Communication
with our Father in Heaven is not a trivial matter. It is a sacred
privilege. It is based upon unchanging principles. When we receive help
from our Father in Heaven, it is in response to faith, obedience, and
the proper use of agency.
It
is a mistake to assume that every prayer we offer will be answered
immediately. Some prayers require considerable effort on our part. True,
sometimes impressions come when we have not specifically sought them.
They generally concern something we need to know and are not otherwise
able to find out."
--Richard G. Scott
The entire talk is below in this link:
http://www.lds.org/general-conference/1989/10/learning-to-recognize-answers-to-prayer?lang=eng