time_track.rb

def time_get
  puts "Please hit Enter to start time tracking"
  
  if gets.chomp == ""
    Time.now
  else 
    time_get
  end
end

def time_stop  
  puts "Please hit Enter again to stop time tracking"
  
  if gets.chomp == ""
    Time.now
  else 
    time_stop
  end
end

def time_track
  start_time = time_get
  puts "Time tracking started at #{start_time}"

  end_time = time_stop
  puts "Time tracking ended at #{end_time}"

  end_time.to_i - start_time.to_i
end

time = time_track

# omg hack - http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/170729
puts [time/3600, time/60 % 60, time % 60].collect {|t| t.to_s.rjust(2, '0')}.join(':')