Dinner leftovers

Some common ways people deal with dinner leftovers:

• Throw it away.
• Force themselves and/or others to consume it.
• Save it for tomorrow, maybe even find a way to enhance it.

If the goal is to minimise waste, and assuming that you're not out in the jungles where you can't preserve or find food, isn't it pretty clear which one is the most reasonable to handle dinner leftovers?