Variables value gets lost in Watchface

Hello everybody,

I added a function to my watchface which isn't working but I really don't have a clue why.

The goal is simply to sum up the min and hours moved on a day. To a certain extend that works but every once in a while he resets and I don't know why. I never reached vaules over 40 min before it got reset for no reason I understand.

Anybody aware of the fault I made?

The view.mc

using Toybox.Lang as Lang;
using Toybox.System as Sys;
import Toybox.WatchUi;
using Toybox.Time.Gregorian as Date;
using Toybox.Application as App;
using Toybox.ActivityMonitor as Mon;


class Last_MoveView extends WatchUi.WatchFace {
    var stepsolds = 0;
    
    var summoved = 0;
    var hoursmoved=0;
    var minmoved=0;
    var minalt = 0;

    function initialize() {
        WatchFace.initialize();
    }

    // Load your resources here
    function onLayout(dc) {
        setLayout(Rez.Layouts.WatchFace(dc));
    }

    // Called when this View is brought to the foreground. Restore
    // the state of this View and prepare it to be shown. This includes
    // loading resources into memory.
    function onShow() {
    }

    // Update the view
    function onUpdate(dc) {
        setsummoved();

        View.onUpdate(dc);
    }

    // Called when this View is removed from the screen. Save the
    // state of this View here. This includes freeing resources from
    // memory.
    function onHide() {
    }

    // The user has just looked at their watch. Timers and animations may be started here.
    function onExitSleep() {
    }

    // Terminate any active timers and prepare for slow updates.
    function onEnterSleep() {
    }

the function:

function setsummoved() {

        var zeit = Sys.getClockTime();
        var stepnews = Mon.getInfo().steps;
        //stepnews =50;
        //summoved =100;
        if (zeit.hour>5) {        //datealt
            if (stepnews>stepsolds+20){      //and (now.min>minalt)
                if (zeit.min>minalt) {
                    summoved=summoved+1;
                    if (summoved>60){
                        hoursmoved=(summoved/60); //summoved % 60;
                        minmoved = summoved % 60;//summoved - (hoursmoved*60);
                    } else {
                        hoursmoved=0;
                        minmoved = summoved;
                    }
                }
            }
            var timeStrings = Lang.format("$1$:$2$", [hoursmoved, minmoved.format("%02d")]);
            var view = View.findDrawableById("summovedDisplay");   //Anzeige Mitte Z3  Uhrzeit der letzten Bewegung 55 85
            view.setText(timeStrings); 
            minalt=zeit.min;
            stepsolds=stepnews;
        }else{
            summoved=null;
            hoursmoved=null;
            minmoved=null;
        }

    }

The Layout:

<layout id="WatchFace">
    <label id="summovedDisplay"    x="55%"     y="85%"     font="Graphics.FONT_XTINY"              justification="Graphics.TEXT_JUSTIFY_CENTER" />
</layout>