I learned that, In my case, advances came in sudden bursts sometimes. I would practice on something for a good period of time and seem to be making little or no progress, even to the point of almost giving up. Then I would get up one morning an sit at the keyboard and I could do it, seemingly out of the clear blue sky. I learned to never give up. So I say, never give up.
Hard work and time are necessary to succeed in learning the piano. Listen to a lot of music, and try to play it. Play with more advanced players when possible. Develop a plan and follow it fully, whether it is with a good teacher, or a carefully selected cd/DVD study course.
It is not easy to learn to play a keyboard well. However, it is very possible to do so. It is according to the desire and determination of the individual as to how far he/she will go.