Here's a cool hybrid exercise that will work your lower body and smoke your core as well.
Goblet Squat to Stepback Lunge
How to do it: Pretty self-explanatory. Grab one or two kettlebells and hold them in the goblet or "racked" position as shown in the video. If you don't have kettlebells, hold one dumbbell at your chest as shown in the picture below.
One squat followed by a stepback lunge with each leg equals one rep. Perform 5-12 reps, depending on your goals.
Why I like it: I find this exercise to be useful for a few scenarios:
1) Travel. It's no surprise to most of you reading that hotels aren't the best-equipped when it comes to their "fitness rooms." The first thing you'll notice is the lack of a squat rack (which would cost less than the myriad machines they have, along with providing countless more uses, but I digress). You'll then quickly notice a bunch of treadmills, machines, and, if you're lucky, a dumbbell rack.
However, more often than not, the dumbbells stop at 50lbs. This is all well and good....I get why they do that. Nonetheless, sometimes those who are a bit stronger run out of ideas with what to do with sub-55lb dumbbells besides doing thirty reps of everything. Since the goblet squat to stepback lunge demands more from you than performing a squat (or stepback lunge) on its own, you can get more out of the lighter dumbbells. Also, with the weight being held at your chest, your entire midsection is going to have work like crazy to keep yourself upright.
Another note here would be if you're in a normal gym with only a few minutes to train and the squat rack is being hogged by a dude doing shrugs for an hour.
2. To use on an "off" day. The more I train, the more I tangibly recognize the truth of Dan Gable's sage advice: "If something is important, do it every day."
Wanna know something that's important? Squatting! Toss in a few of these babies on your off days to get some bloodflow going, "unglue" yourself after a long day at the office, and ingrain some proper motor patterns.
Not to mention, the stepback lunge is the most "knee friendly" of all the lunge variations, on top of the fact that it doesn't typically invoke too much post-workout soreness due to lessened deceleration demands (as you'd experience during a forward lunge or walking lunge).
If you are using these on an off day, go light with the weight selection. No need to be a superhero, big guy.
3. Accessory Work. We've also programmed these for people as part of their main training day, for a few reasons. Maybe we're trying to give their CNS a break from the barbell (ex. if they're overwhelmed with in-season demands or are doing a lot of extra work outside SAPT with the military, their sports teams, etc.). Or, sometimes, we're just trying to deload their spine a bit and take some time away from barbell squatting/lunging. Or, maybe we just want to make them hate life.
4. Conditioning Work. As noted above, these things have the potential to make you hate life. Toss them in from time to time to develop that good ol' work capacity.
**Addendum: This also makes a great variation for sandbag work. See the video below in which me and a few buddies of mine did these for part of an outdoor workout.