I've read several posts and have now found the answer, I hope someone can
help me.

My situation is this... I am working on a 'cash flow' analysis that, at one
point, takes positive cash flow and applies it to a loan payment.... Put
simply, when ever the cash flow is positive it would automatically be added
to a payment amount. But I want this to be conditional and only applied when
the cash flow reaches certain amounts, so if cash flow is negative the amount
is 'ignored'.

Here's what I have:
Cell 1, total cash flow: =SUM(K117-K119-K121-K123+K125)+J131
Cell 2, payment amount: =(J117-J121)

So basically anytime Cell 1 is over a certain amount it would add that
amount to the total result in cell 2, but if cell 1 is below a set amount
it's ignored.

ideas?