Confession time: For most of my life, I thought of exercise merely as a way to punish my body for being gross , warp it into thinness, and burn, burn, burn every calorie I'd ever eaten. When I was being "good," that meant hours on the elliptical (or whatever machine was on-trend and not that hard), combined with obsessive step counting. Even when I was in a yoga phase, I'd find myself whipping faster and faster through vinyasas, looking like a hamster on a wheel. Because, you know, strength and flexibility are nice and all, but cardio — that's what really matters, right?My relationship with fitness has evolved tremendously in the past two years. It's taken constant effort to retrain my brain to recognize exercise as a means of achieving physical and mental health, and while it's not always easy (what with the rest of the world still shrieking about thigh gaps), this attitude has helped me maintain a consistent level of exercise for the first time in my life. So, take that, thigh gaps.But old habits die hard, especially when they're mental habits. And recently, I realized that I had one old habit still haunting me through every workout: cardio mania.Even those of us who only have a "magazine level" of education in fitness know that you're supposed to have a balanced exercise routine that includes cardio, strength training, and stretching. But most of us — especially women — still operate under the idea that reeeeaaallly we just need some good, sweaty cardio. Certainly, I thought this. And even when my fitness goals shifted from weight loss to overall health, I still treated cardio like the meat of the meal. Everything else was gravy; I could do without it. Without cardio, I might as well not eat at all.It wasn't until I started consistently trying other forms of exercise in addition to my gym time that I realized how much my body had been missing. Only when I developed a truly balanced routine did everything get better: My posture changed, my body composition felt different, and I was flying up the four flights to my apartment with ease. Before, I thought if I just worked my heart muscle enough, that would make the stairs easier. But no — it turned out I had to develop my thighs, calves, and glute muscles, too. Forgive me, but: duh.Once the cardio spell broke for me, I finally began to hear what fitness professionals had been saying for years: We are all hyper-focused on cardio, and it's doing us no good. I sat down with Cadence Dubus , owner of fitness studio Brooklyn Strength , who is constantly trying to combat the cardio fixation in her own clients and get them to that "duh" moment. How did cardio become such a dominant trend? Why are we so hooked on it? What are we getting wrong here, and how can we get it right? Here are some myths, facts, and surprising truths we all need to learn about cardio.