I'm typing numbers out (int and double) and there is a problem

using System;

namespace Treehouse.FitnessFrog
{
  class Program
  {
      static void Main()
      {
          double runningTotal = 0;
          bool keepGoing = true;
          while (keepGoing) 
        {
            // Prompt the user for minutes exercised
            Console.Write("Enter how many minutes you have exercised or type \"quit\" to exit: ");

              string entry = Console.ReadLine();

              if(entry.ToLower() == "quit")
              {
                 keepGoing = false;
              }
              else
              {                
                  try
                  {
                     double minutes = double.Parse(entry);

                     if(minutes <= 0)
                        {
                          Console.Write(minutes + " is not an acceptable value. ");
                          continue;
                        }

                      else if(minutes <= 10)
                      {
                          Console.Write("Better than nothing I suppose. ");
                      }
                      else if(minutes <= 30)
                      {
                          Console.Write("Hell yeah! ");
                      }
                      else if(minutes <= 60)
                      {
                          Console.Write("Am I seeing a warrior in training? ");
                      }
                      else
                      {
                          Console.Write("Stop showing off! But don't stop exercising though, it's     good for you! ");

                        runningTotal = runningTotal + minutes;

                      }
                  }
                   catch(FormatException)
                  {
                      Console.Write("That is not a valid input. ");
                      continue;
                   }

            // Add minutes exercised to total
            // Display total minutes exercised to the screen#
            Console.WriteLine("You've entered " + runningTotal + " minutes");
            }
            // Repeat until user quits 
        } 
            Console.WriteLine("Goodbye");
      }
  }
}