There are 2 main categories that we can fit cardio into:
Low Intensity Steady State Cardio (LISS)
High Intensity Interval Training (HIIT)
As the names suggest, the key difference is in the intensity of the training.
LISS cardio is low intensity, so shouldn’t be overly taxing and is likely to be of longer duration e.g. 30 minutes. It can boost metabolism and burn calories, but on the downside it can be time consuming and boring. Examples include walking, jogging, cross trainer etc.
HIIT training is using short bursts of all out intensity, interspersed by shorter periods of rest or much lower intensity. For example, you could put a cross trainer on a medium to high resistance level and do 30 seconds of all out work, followed by 20 seconds of very slow work. Then repeat the 30/20 seconds over and over again until you have completed 10 minutes. If you are able to do HIIT for more than 10 to 12 minutes, you aren’t working hard enough. You can get creative with HIIT and use it for conditioning your body as well as burning calories. Try hitting a tyre with a sledgehammer for 20 seconds then rest for 10 seconds. Repeat for 8 to 10 minutes. Another option is an all over body exercise like holding two dumbbell’s (light) and repeatedly performing a squat into a bicep curl or shoulder press. Go all out for 20 seconds, then rest for 10 seconds. Repeat for 8 to 10 minutes.
Both LISS and HIIT can have results, so find out what works best for you. HIIT is my personal choice as it never gets boring, and is quickly over which frees me up to go about my busy life. The main thing is that you pick cardio that works for you and that you enjoy. If it gets boring, you are more likely to skip.