gistfile1.cs

public interface ITask
{
    void Execute();
}

public class SimpleTask : ITask
{
    public void Execute()
    {
       Console.WriteLine("X");
    }
}

        public static void Schedule<T>(TimeSpan timespan) where T : ITask
        {
            var x = Activator.CreateInstance<T>();
            Schedule(timespan, x.Execute);
        }

        private static void Schedule(TimeSpan timespan, Action task)
        {
            Task.Run(async () =>
            {
                while (true)
                {
                    task();
                    await Task.Delay(timespan);
                }
            });
        }