How to uncheck checkboxes with Date Macro

I am new to VBA and this Forum. I am trying to create a bit of a tricky Excel Spreadsheet. I currently have a spreadsheet that records our battery recharging information(Crate #, Date last charged, Date for Recharge). This spreadsheet currently has a Macro that when opened sends an email to certain employees as to which crate requires charging. I would like to change it so that instead of manually entering the dates you check a checkbox and the next date automatically comes up. That part is easy. The difficult part is getting the checkbox to uncheck when the date for recharge passes. The code below unchecks the checkboxes but how do I modify it to uncheck when date is less than today?

Sub ResetAllCheckboxes()
    With ActiveSheet
        For Each chk In .CheckBoxes
            chk.Value = False
        Next
    End With
End Sub

Any help would be appreciated!

Thanks,

Ash