We all know the guy that walks around the gym, happily swinging his shoulders and puffing his pecks.

He probably spends most of his time walking back and forth between the incline bench, the preacher curl and the mirror to take another selfie. Don't be like this guy.

Muscles are great and upper body work is not to be neglected but if it's most or all of what you do, you are doing it wrong. Want to be fit? Start with building your legs and core. The rest will follow suit.

But even we can admit that the typical leg workout can get boring, static and downright depressing. That's why we put together this 15 minute finisher that will make any workout a leg workout.

Let's start by talking a bit about the movements that comprise this work out. There are only two of them, they don't require any equipment but they do require some attention to form.

First up, the lunge. You may think you know how to do a lunge, but I would put good money on the fact that most people don't, because we have all been misinformed. The best article that I have seen on the subject is from our good friends at Furthermore.

We have traditionally been taught a few cues on the lunge and raise your hand (don't actually though) if these sound familiar to you: Keep your back straight and perpendicular to the floor, don't let your knee pass beyond your toe, chest up and look straight ahead.

Those are good rules and generally reinforce good form, but as the article points out, you could be placing a lot of unnecessary stress on your knee joints and forgo building strength, power and mobility in your hip joint.

Try instead to hinge slightly at the hip and the knee so that both exceed the customary 90° angle (notice slightly is underlined) while keeping your shoulders back and slightly depressed.

Now onto the wall sit. Unlike the lunge, a perfect wall sit begins and ends with strict 90° angles in both the knee joint and the hip joint.

Make sure to start with your back flat against a wall with your feet about two feet in front of you. Slowly sink down, keeping your shoulder blades against the wall, until your thighs are parallel to the floor and your knee joint forms that perfect 90° angle. This is the position but just one more note, your hands, elbows and arms should not be touching anything but air. Acceptable positions are prayer hand emoji and frankenstein arms (straight out in front).

Now that we understand the movements, let's get down to business.

The workout is as follows:

20 Alternating lunges (10 x per side)
:30 Wall sit
18 Alternating lunges (9 x per side)
:30 Wall sit
16 Alternating lunges (8 x per side)
:30 Wall sit
14 Alternating lunges (7 x per side)
:30 Wall sit
12 Alternating lunges (6 x per side)
:30 Wall sit
10 Alternating lunges (5 x per side)
:30 Wall sit
8 Alternating lunges (4 x per side)
:30 Wall sit
6 Alternating lunges (3 x per side)
:30 Wall sit
4 Alternating lunges (2 x per side)
:30 Wall sit
2 Alternating lunges (1 x per side)
:30 Wall sit

    Move through each movement with absolutely no rest and pretty soon you will be completely fired up. Not to mention, both movements are great for strengthening the quadriceps as well as the old glutes.

    If you are looking for more of a crazy challenge, do the odd sets of lunges as well followed by additional sets of wall sits. Too easy? Start by adding light dumbbells for the lunges or holding a plate while you do the wall sits. 

    So don't skip leg day and especially don't skip this sweat of the week.