How to run the timer tasks asynchronously?

public class Timer
    {
        public delegate void Timer_Tick(object sender, EventArgs e);
        public event Timer_Tick Tick;
        System.Threading.Thread TimerThread = null;

        public Int32 TimeoutFrequency {get;set;}
        public Boolean TimerWorking {get;set;}

        public void Start()
        {
            this.TimerWorking = true;
            this.TimerThread = new System.Threading.Thread(new System.Threading.ThreadStart(RunTimer));
            this.TimerThread.IsBackground = true;
            this.TimerThread.Start();
        }

        public void Stop()
        {
            this.TimerWorking = false;
            if (this.TimerThread.ThreadState == System.Threading.ThreadState.Running)
                this.TimerThread.Abort();
        }

        private void RunTimer()
        {
            Int32 inc = 0;
            while (this.TimerWorking)
            {
                inc++;
                System.Threading.Thread.Sleep(1000);
                if (inc >= this.TimeoutFrequency)
                {
                    Tick(this, new EventArgs());
                    inc = 0;
                }
            }
        }
    }