C# Online Compiler | .NET Fiddle

using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;

namespace WatchLoop
{
    public class Program
    {
        static public void Main(string[] args)
        {
            var cancellationSource = new CancellationTokenSource();

            WatchExeTime2(InformAboutLongTime, cancellationSource.Token);

            Console.WriteLine("Going to execute a long time operation.");

            Thread.Sleep(1600);
            cancellationSource.Cancel();

            Console.WriteLine("The long time operation executed");
        }


        static private void InformAboutLongTime()
        {
            Console.WriteLine("The operation in progress, please wait");
        }
        
		static private void WatchExeTime(Action action, CancellationToken cancellationToken)
        {
            Task.Run(
            () =>
            {
                var sw = new Stopwatch();
                sw.Start();

                var invokeAt = TimeSpan.FromMilliseconds(200);

                while (true)
                {
                    if (cancellationToken.IsCancellationRequested)
                    {
                        return;
                    }

                    if (sw.Elapsed > invokeAt)
                    {
                        action();
                        sw.Restart();
                    }
                }
            },
            cancellationToken).ContinueWith(t => { }, TaskContinuationOptions.OnlyOnFaulted);
        }


        private static void WatchExeTime2(Action action, CancellationToken cancellationToken)
        {
            Task.Run(
            () =>
            {
                var waitFor = TimeSpan.FromMilliseconds(200);

                while (cancellationToken.IsCancellationRequested == false)
                {
                    var cancelled = cancellationToken.WaitHandle.WaitOne(waitFor);

                    if (cancelled)
                    {
                        break;
                    }

                    action();
                }
            },
           cancellationToken).ContinueWith(t => { }, TaskContinuationOptions.OnlyOnFaulted);
		}
    }
}

 
using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
​
namespace WatchLoop
{
    public class Program
    {
        static public void Main(string[] args)
        {
            var cancellationSource = new CancellationTokenSource();
​
            WatchExeTime2(InformAboutLongTime, cancellationSource.Token);
​
            Console.WriteLine("Going to execute a long time operation.");
​
            Thread.Sleep(1600);
            cancellationSource.Cancel();
​
            Console.WriteLine("The long time operation executed");
        }
​
​