Barbell Hip Thrust

Awesome assistance exercise for the squat and deadlift. Develops incredible glute, hamstring, and hip strength, specifically through hip extension. Very applicable to grapplers/fighters, who spend a lot of time on the floor.

*Note: can be done without weight. Work up to a barbell by using dumbbells or plates.

"Real" Leg Lifts

Far too often, people perform leg lifts by simply lifting their feet/legs off of the ground. HUGE MISTAKE! It becomes an exercise for the hip flexors, as opposed to the rectus abdominus (abs!).

In order to fully recruit the abs, it is imperative that you raise your feet/legs off of the ground AND lift your butt up, as well! Picture this: there is a rope tied around your ankles. When your legs are perpendicular to the floor, picture someone pulling the rope toward the sky, thus causing your butt to lift off of the ground. If you're doing it correctly, you should feel a pretty intense contraction in your abs.

Pushups

These will never go out of style. They're very space efficient, versatile, and provide a great workout for your chest, shoulders, triceps, biceps (seriously, do enough of these and your biceps feel it), lats, abs... Not too bad for a basic, well-known, and, quite frankly, under-utilized exercise. Everyone can benefit from these.

Note: Don't tuck your head or tilt it back. Keep it, along with your spine, in a neutral position. Check your form by placing a broomstick on your back. The broomstick should be in constant contact with your head, upper back, and butt throughout the entire range-of-motion.

Mountain Climbers

Sure, these look easy, but incorporate them into a circuit or perform them for an extended amount of time on their own, and these will destroy you. They are great for shoulder health, core endurance/strength, and also provide a good dynamic stretch for your hip flexors, glutes, and hamstrings

Jumping Jacks

Yup, just like your elementary school PE teacher used to make you do... Can be used as a good conditioning exercise AND they are very good at priming (read: waking up) the CNS, as they are inherently "explosive" in nature.

Burpees

Great full-body conditioning exercise. They take up very little space, require no equipment, and can be done by any exercise level.