Ramadan is a like a cloud containing abundance amount of rain, capable of filling anything placed under it. It is up to us how much we want to gain from it, a cup full or a tank full. The more we exert ourselves in Ramadan to perform ibadah, the more we will reap its rewards.
A person who does deeds to show others is like a person who fills his bag with stones instead of gold. The stones will only make the bag seem heavy to others, but will be of no use when he needs to purchase something. Similarly, the insincere person will only appear to be pious.