Also read into the SMILE study (Standard Medical Intervention and Long-term Exercise, conducted at Duke University), which found that vigorous exercise three times a week for half an hour or forty-five minutes reduced symptoms of depression as effectively as those on antidepressants. And those who had exercised were more likely to be partially or fully recovered or were less likely to have relapsed than the group that had only taken medication (Zoloft) or taken medication and exercised.

Sean, cardio DOES make many people happy. Read into it more.

“working in some body weights just to let the body know it needs to stay strong” – I’d say only if your sport would benefit from that type of training. Not from an aesthetic standpoint.

“but cardio is equally or more important for the fat loss bit” – Having cardio being the cornerstone of your fat loss strategy is not a smart idea. Diet is essential to fat loss, use cardio if you enjoy it or need it to in order to get a larger deficit than you’re willing to by diet along, which should be rare, by the way, if you are approaching you’re dieting right (read: give a long enough time span to lose the fat).

It doesn’t matter if you have a lot of fat to lose or a little – A deficit is a deficit. If you want to eat 2000 cals everyday (because your maintenance is 3000, for example), you can achieve that by only eating 2000 calories, or by eating 2500 cals and doing cardio to burn off 500 cals. Many people counter this by saying that that cardio will make more of the deficit come from fat instead of muscle. However, recent studies have not been supporting this theory http://www.ncbi.nlm.nih.gov/pubmed/19833807

Also, you don’t always need a very large deficit unless you have some competition, photoshoot, etc. coming up soon. Otherwise, most of the time you are better off losing fat in a longer time period in order to keep your muscle mass.

The only exception I would have for any of this is for very light female athletes. In order to create a reasonable deficit, they would need to sacrifice a large percentage of their daily calories, which might not allow them to get all the micro-nutrients they need from food. So in that case, cardio might be a good idea to create some of that deficit, allowing them to heat nutritional foods.

Large caloric deficit? Either you achieve that by diet, or by diet + cardio. Same deficit though.

Looking at cross trainers is highly subjective. Many people would say that natural bodybuilders look the best, yet some of them do not do any cardio at all. Cross trainers are just one subgroup that care about how lean they are, so they are going to pay more attention to their diet than say, a powerlifter, who doesn’t care at all how much he eats as long as it’s a ton.

but cardio is equally or more important for the fat loss bit

I agree you will delve into muscle when you do cardio but you can protect against this with diet (PRE CARDIO PROTEIN 20-30G) AND caffeine as weel as working in some body weights just to let the body know it needs to stay strong (boxers the ultimate sportsmen arguably use circuit training).