You want to lose weight. What's the first way to get that done that pops in your head? Reduce calories and do a bunch of cardio. Like miles and miles and miles. Well......kinda.
Plodding away at hours and hours of cardio at a sub-optimal heart rate level doesn't burn fat the way most people are looking for. To achieve the lean, muscular, chiseled look that I usually hear is a goal, you HAVE TO LIFT WEIGHTS. Lifting weights builds lean muscle mass which in turn burns more calories throughout the day. Weight lifting creates what is commonly referred to as an 'after burn' where your body continues to burn calories at a higher rate for longer AFTER you workout than it will after your cardio workout.
Not ready to give up cardio? Good, you shouldn't give it up! Steady state cardio does have it's benefits. It trains your heart and lungs to work at an elevated rate over a longer period of time, making them stronger. To achieve more fat burn from cardio, you have to up the ante. This is where the HIIT (high intensity interval training) cardio comes into play. Think sprint work, or alternating between burpees and squats. The idea is that you get your heart rate high, higher than you can sustain for very long, then let it come back down and repeat that process for about 20 minutes or so.
Bottom line? You need to lift weights, do high intensity cardio and some steady state cardio. Good news - you won't get bored!