If you've ever skipped out on your workout because you were a) short on time, b) in a cramped space, or c) lacking your usual dumbbells or resistance band, you're definitely not alone. After all, it's easy to buy into the idea that if the scene isn't perfectly set for a workout, you're better off just waiting to do it until the timing's right.

But the idea that banging out a workout when you don't have access to your usual equipment or space is one that trainers are quick to debunk. Sure, they know their way around a gym floor and a smart workout program, but they also know that when you're traveling, ultra busy, or just don't feel like dealing with the gym, a routine of challenging bodyweight exercises will get the job done.

Not to mention, bodyweight exercises can be just as effective as the moves you do with equipment. With the help of a little gravity, your own body is an amazing tool for challenging your muscles.

Here are the equipment-free exercises that top trainers swear by, for their clients and for themselves. Whether you're looking for a boost of cardio or you want to work your legs, butt, core, arms, or all of the above, there's a go-to exercise for everyone to keep in their back pocket. No whistles or bells—er, kettlebells—required.

Demonstrating the moves is Cookie Janee, a background investigator and security forces specialist in the Air Force Reserve.