 
         set {
             userDefaults.setObject(newValue, forKey: CountdownViewModel.BirthdayKey)
-
-            if !startTimer.executing.value {
-                startTimer.apply().start()
-            }
         }
     }
 

    private let userDefaults: NSUserDefaults
    public let active = MutableProperty<Bool>(false)
    private let startTimer: Action<Void, NSDate, NoError> = Action { timer(0.1, onScheduler: QueueScheduler()) }
    public let age = MutableProperty<Double?>(nil)

    public var birthday: NSDate? {


        if let birthday = birthday {
            age.value = ageForBirthday(birthday)
        }

        // Skip initial value
        active.producer.skip(1).startWithNext { [unowned self] active in
            if let startTimerDisposable = self.startTimerDisposable {
                startTimerDisposable.dispose()
                self.startTimerDisposable = nil
            }

            if active {
                self.startTimerDisposable = self.startTimer.apply().start()
            }
        }

        age <~ startTimer.values.map { [unowned self] _ in
