During a 30 minute cardio workout, when reaching the minute prior to 5, 10, 15, 20, 25, and 30, I do a one minute full out sprint. This makes the time pass so much faster and expends significantly more calories.
Added bonus: I have to cool down after my sprint at minute 30, which extends my ...
Keep in mind a great way to eat and exercise that you can see yourself doing 20 years from now. This frame of thinking helps us move away from a "dieting mentality" and towards a "lifestyle change mentality", which will keep your results lasting for the longterm...no more rinsing and repeating!
I have three rules:
First: Earn meal #1 with 30 min. of cardio
Second: Earn meal #2 with 6 glasses of water
Third: earn meal #3 with meeting weight training goals
In other words, I really do earn my food!