title: C# + Format TimeSpan
body: <p>I am trying to format a TimeSpan element in the format of "[minutes]:[seconds]". In this format, 2 minutes and 8 seconds would look like "02:08". I have tried a variety of options with String.Format and the ToString methods, but I get a FormatException. This is what I'm currently trying:</p>
  
  <pre><code>DateTime startTime = DateTime.Now;
  // Do Stuff
  TimeSpan duration = DateTime.Now.Subtract(startTime);
  
  Console.WriteLine("[paragraph of information] Total Duration: " + duration.ToString("mm:ss"));
  </code></pre>
  
  <p>What am I doing wrong? How do I format a TimeSpan element using my desired format?</p>