Cardio fun :-)

You can do this with a pack of cards, or if you don't want to look silly download a free random number generator app.

If you are using a number generator set the max number to 13, ie ace to king.

Using a tredmill, Warm up for 5 mins and then slow to a walk and turn over a card or get a random number from your app.

Whatever number or card you get will be the effort level.

1-3 easy pace 1 min
4-5 can talk easy enough 1 min
6-7 out of breath 1 min
8-9 can't talk, uncomfortable 1 min
10 + flat out!! 30 seconds only

Do this for 20 mins, the time will fly by!!

Don't forget to slow to walking when it's time to turn the next card :-)