Excel Calculate worksheet call cell that changed

I'm using the Excel Private Sub Worksheet_Calculate() function, but I only want to run my code if the value of the cell that has changed has changed to 0, if not I want to bypass all my code. My spreadsheet updates quite often so I'm trying to not bog down the computer. But anyways, is there an if statement that I can write to check if the value that has changed has changed to now equal 0. Thanks!