A table or a desk
A long string
Tape a string to one side of a coin and take the other end of the string and tie it to a drawer of a desk or a table.
Pull back the coin to a height till it touches the front of the desk. Make sure that the string is kept straight all the time.
Now release the coin. You will see that that the coin moves from one end to the other end, but with each motion, the distance decreases.
How does this work?
The amount of energy a body gives out is the amount of energy it takes. When you pull back the coin on to a certain height, you provide it with a certain amount of energy in order to move from one point to the other. But with each movement, the coin begins to lose energy and hence, the distance covered from one point to another decreases.