Here's one way you could do it :
View attachment 107297
I have not shown all the connections to the 555; just how the output pin 3 drives a transistor.
The transistor can be, for example, a TIP120 or TIP121
The resistor value can be in the 1k to 5k range.
The diode can be, for example, a 1N400x, where x is in the range 1 to 7.
The motor connects to the collector (column 16) and the +ve rail (Y2).
N.B. This layout is shown for simplicity but is not ideal, because motor current is passing through the breadboard connectors (which are intended for low currents only).