The Mona Fartlek is a training session Australian long distance runner Steve Monaghetti used throughout his career.  

It's a session that involves some hard fartlek running - perfect if you are short on time but need to get a good workout under your belt. The whole session can be done in under 30 minutes.  

The session looks like this:

Warm up (~ 5 mins)
2x90sec,
4x60sec,
4x30sec,
4x15sec
Cool down (~5 mins)

Each interval has an equivalent recovery or slow jog period in between. ie: 90 seconds hard, 90 seconds recovery, 90 seconds hard, 90 seconds recovery, 60 seconds hard, 60 seconds recovery, 60 seconds hard, etc.  

The recovery time in between can be as fast or slow as you like but your focus should be on running the interval sessions as quickly as you can whilst maintaining the pace throughout the interval. By the time you reach the 15 seconds intervals you should feel pretty spent but should still aim to be running flat out.  

If you are new to running you'll find the session pretty challenging so you may want to do a shortened version until you feel more comfortable.