Reducing a variable every x seconds [Arduino Uno]

Projects General Guidance
5 
    static unsigned lastSeconds = 0;
    if (Seconds > lastSeconds )
    {  // Time has changed
        lastSeconds = Seconds;
        // Starting at 10 seconds, every 5 seconds,  decrement the Variable by 1 until it reaches 0.
        if (Seconds >= 10 &&  (Seconds % 5) == 0  && Variable >= 1)
        {
            Variable--;
        }
    }