Unlike some traditional desk jobs where you learn the tricks of the trade during orientation and then repeat the same duties every day, fitness is always changing, which means you'll have to do the same. “Exercise science is a constantly evolving field," Matthews says. "In order to ensure that your students receive the safest and most effective class experiences, you must understand that not only will you be teaching classes, you'll also be taking classes (workshops, conference sessions, online courses, webinars, etc.) to be the best instructor you can be.” That means (if you want to stay competitive and improve your skills) you can plan on investing your money, time, and energy on a regular basis for continuing education. But if you choose fitness as your career, there's no doubt you'll find the latest research and training techniques fascinating.