DateTime startTime = DateTime.Now;

 DateTime endTime = DateTime.Now.AddSeconds( 75 );
 
 TimeSpan span = endTime.Subtract ( startTime );
 Console.WriteLine( "Time Difference (seconds): " + span.Seconds );
 Console.WriteLine( "Time Difference (minutes): " + span.Minutes );
 Console.WriteLine( "Time Difference (hours): " + span.Hours );
 Console.WriteLine( "Time Difference (days): " + span.Days );

====================================================================

Time Difference (seconds): 15
Time Difference (minutes): 1
Time Difference (hours): 0
Time Difference (days): 0