I love HIIT (high intensity interval training) first and foremost because of the intensity. I am a somewhat competitive person, so it allows me the opportunity to mitigate my level of intensity. I like being challenged, whether it’s because I am going up in weight, or the time format changes, etc. There is just a level of fun and accomplishment that comes from pushing yourself past your expected limits. Plus being able to work on strength, endurance, cardiovascular capacity, core and other things in less than an hour can't be beat.
Here are some tricks for upping the intensity of your HIIT workout.