DouKaku?

using System;
using System.Timers;

class Program {
    static void Main(string[] args) {
        using(Timer timer = new Timer(1000)) {
            timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);
            timer.Start();
            bool flag = true;
            while(flag) {
                ConsoleKeyInfo conKeyInfo = Console.ReadKey(true);
                ConsoleKey conKey = conKeyInfo.Key;
                switch(conKey) {
                case ConsoleKey.P:
                    timer.Enabled = !timer.Enabled;
                    break;
                case ConsoleKey.Q:
                    flag = false;
                    break;
                }
            }
           timer.Close();
        }
    }

    static void timer_Elapsed(object sender, ElapsedEventArgs e) {
        Console.Out.WriteLine("a");
    }
}