Ladder

for this format pick 3 or four moovements.  they should be on more difficult side. set the 25 minute timer to count down mode.  do aech moovement 21 times to stsrt  then repeat the same moovements 15 times  then 12 times  then lastly 9 times.  the challenge is to beat the clock, complete all the reps before time expires.  this is a rest as neede format and will result in as much cardio as u need.  I always try to get what i need out of any practice. thats great advice. 

 this practice can also be modified to a 15 – 12 – 9 – 6 rep format   still very challenging