OK I am going to disagree with both of you, and agree at the same time.
Kiwi is right about 90% of people hating static state cardio. Only freaks like me are happy plodding along the pavement multiple times a week as part of their training.
That doesn't mean 90% of people can't stand cardio, in the same was as not liking carrots doesn't mean not liking vegetables.
Cardio vascular training is anything where the pulse rate is elevated through activity for a prolonged duration, usually stated but debateable minimum of 20 minutes. This doesn't have to be steady state, it can be weight circuits, body pump, active dance, boxing training and various other things as long as the pulse is kept high and you don't go into oxygen debt too often. I would say at least 90% of trainers would find something they enjoy within the full potential cardio repertoire.
I will totally challenge the claim that running will mean losing muscle mass. I do get a bit tired of the cardio makes you puny argument I see a lot, it isn't true and never has been, in fact done well it can improve the ability to gain mass.
I do a plod run 3 times a week, over 5 miles in length, an interval session once a week that takes over half an hour. I walk a lot on days when not running, so plenty of cardio there most days. I am genetically designed to hide behind lampposts so gaining mass is very difficult for me. In the last 2.5 years I have gained over 20 pounds in weight, most of this has been lean mass, this hasn't been beginners gains as I have been training since I was 18 and I am 40 now.
I am not a pro body builder, never wanted to be but I am far from puny being able to comfortably bench my bodyweight, squat and deadlift double all for reps.
Like it or not the aerobic system pays the energy bills in your body, whatever source you pull from initially this will pay the final balance, anaerobic or CP are like having energy on credit, the aerobic pays the balance with interest. Improving the efficiency of your CV systems means this debt is paid of faster and you can train harder, therefore gain more mass.
There are body builders who get out of breath on the stairs, but they are rarely the champions, because they are not fit enough to train at the level champions need to. When I was training in an old roid pit one of the guys there won junior Mr Universe, so fair to say he was pretty good. At two or 3 sessisons a week he would do some light weight work as a circuit with short gentle cardio machine warm up and cool down, total weekly time was an hour or less. Nothing intense enough to interfere with his real training but enough to give him a very healthy CV system, vascular look and the ability to train at a level those not doing any cardio couldn't match.
I do get very bored of cardio slamming in general. It generally comes from people who don't understand what it really is and promoting the idea of never doing any cardio is promoting one of the biggest causes of death worldwide, heart failure.
Rather than deeming cardio useless and ignoring how important heart and lung health are, find things that strengthen them that people enjoy. If this is plodding around on machines or pavements get them a straight jacket but let them do it. If like most they hate this give them circuits or something else instead, keeping them aware this is still cardio so will improve their overall health.
Fat loss wise, this has to be an overall thing as stated, diet is always key and getting this right takes a bit of care. Resistance training and cardio can be combined or separated but variation in training benefits all including those wanting fat loss.
I have said this so often it should be tattooed on the screen. Priority 1 is enjoyment. If someone enjoys a less efficient method and hates the most efficient, explain the results will be slower, if they are happy to take longer let them go. People quit more often through hating what they do than lack of results.
