Surplus is the extra left over from a transaction. Surpluses can be leveraged to make change.
There are two ways to leverage surpluses:
Make surpluses in an unrelated way and route them to where they are needed.
or
Do what creates the surpluses.
If you want to make change you need to be doing one or the other.
How do you create surplus?
Jon Dale 
Sometimes surplus can be “found” by decreasing cost as well. Currently I use surplus to inch myself toward my goal of financial freedom and independence. You’re right, creating the surplus and directing it can mean change.
Jake,
Thats a really good point.  Thanks for commenting.
Jon