Ok, I think I may have come up with a metaphor to help me understand (it's how I understand the best).
If I pour 5 liters of water into a bucket, then I make six holes, only 5 liters of water can come out of this bucket.
But if I take all day, drip by drip, to fill up the bucket, then I make six holes, the water will spray out much more quickly than it took me to fill the bucket.
In other words, the amount of energy I put into the system remains constant, but the machine increases the force applied to the object.
Is that a good metaphor?