Format Exception

  {
      int runningTotal = 0;
      bool keepGoing = true;

      while (keepGoing)
      {
          // Prompt the user for the minutes exercised
        System.Console.Write("Enter how many minutes you exercised or type \"quit\" to exit: ");

        string entry = System.Console.ReadLine();

        if(entry == "quit")
        {
          keepGoing = false;
        }
        else
        {
           try
           {
             int minutes = int.Parse(entry);
                    if(minutes <= 0)
                {
                  System.Console.WriteLine(minutes + " is not a valid entry");
                  continue;
                }
                else if(minutes <= 10)
                {
                  System.Console.WriteLine("Better than nothing right?");
                }
                else if(minutes <= 30)
                {
                  System.Console.WriteLine("Keep it up Hot Stuff!");
                }
                else if(minutes <= 60)
                {
                  System.Console.WriteLine("You must be traing to be a ninja warrior");
                }
                else
                {
                  System.Console.WriteLine("Now you're just showing off");
                }


                // Add minutes exercised to total

                 runningTotal = runningTotal + minutes;

                // Display total minutes
              System.Console.WriteLine("You've exercised " + runningTotal + " minutes");
           }
           catch(FormatException)
          {
            System.Console.WriteLine("That is not a valid input.");
            continue;
          }              

        }
      }
        // Repeat until the user quits
      System.Console.WriteLine("Goodbye");

  }